feat(map): mark a station you want to contact in unworked grids

- New MarkedStation model + ISettingsRepo/SettingsRepo persistence
  (single JSON key markedGridStations, org.json only)
- MapState/MapViewModel: markedGrids state, Set/RemoveMarkedStation
  actions; marks auto-clear once the grid becomes worked
- MaidenheadGridOverlay: red fill (alpha 90, same as green worked
  fill) for marked grids at both zoom levels; first-call label mode
  shows the marked callsign in pale yellow on red cells
- MapScreen: unworked-grid dialog gains a 'mark a station you want
  to contact' button + callsign input dialog; marked row shows red
  callsign, 'Marked' in the count column, marking date, delete icon
- i18n: values/ + values-zh/ (grid_mark_*)

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MaidenheadGridOverlay.kt

@@ -64,6 +64,11 @@ class MaidenheadGridOverlay : Overlay() {
         style = android.graphics.Paint.Style.FILL
         color = Color.argb(90, 76, 217, 100)
     }
+    // 标记(想通联)网格填充: 红色, 透明度与绿色 workedPaint 一致(alpha 90).
+    private val markedPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = android.graphics.Paint.Style.FILL
+        color = Color.argb(90, 255, 59, 48)
+    }
     private val roamStripePaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
         style = Paint.Style.STROKE
         strokeWidth = 14f
@@ -87,6 +92,11 @@ class MaidenheadGridOverlay : Overlay() {
     /** Worked gridsquares (4-char, uppercase) to highlight, e.g. {"OL62", "PM95"}. */
     var workedGrids: Set<String> = emptySet()
 
+    /** Marked gridsquares (4-char, uppercase) — unworked grids the user has
+     *  marked a station they want to contact in; drawn red, same alpha as the
+     *  green worked fill. Value carries the marked callsign for label mode. */
+    var markedGrids: Map<String, com.rtbishop.look4sat.core.domain.model.MarkedStation> = emptyMap()
+
     /** Grid-mode first-call labels: label worked (green) cells with the first
      *  callsign worked in that grid instead of the Maidenhead code; non-worked
      *  cells get no label at all. Only meaningful at sub-square zoom. */
@@ -189,6 +199,9 @@ class MaidenheadGridOverlay : Overlay() {
                         if (cellLabel(lat, lon, zoom) in workedGrids) {
                             canvas.drawRect(xLeft, yTop, xRight, yBottom, workedPaint)
                         }
+                        if (cellLabel(lat, lon, zoom) in markedGrids) {
+                            canvas.drawRect(xLeft, yTop, xRight, yBottom, markedPaint)
+                        }
                     }
                 }
             } else {
@@ -215,6 +228,22 @@ class MaidenheadGridOverlay : Overlay() {
                         canvas.drawRect(xLeft, yTop, xRight, yBottom, workedPaint)
                     }
                 }
+                for (grid in markedGrids.keys) {
+                    val cell = gridCellBounds(grid) ?: continue
+                    for (turn in -colRepeats..colRepeats) {
+                        val dLon = turn * 360.0
+                        if (cell.lonRight + dLon <= leftLon || cell.lonLeft + dLon >= rightLon) continue
+                        val yTop = projectionToY(projection, cell.latTop) ?: continue
+                        val yBottom = projectionToY(projection, cell.latBottom) ?: continue
+                        val xLeftBase = projectionToX(projection, cell.lonLeft, centerLon, worldWidthPx) ?: continue
+                        val xRightBase = projectionToX(projection, cell.lonRight, centerLon, worldWidthPx) ?: continue
+                        val xLeft = xLeftBase + turn * worldWidthPx.toFloat()
+                        val xRight = xRightBase + turn * worldWidthPx.toFloat()
+                        if (xRight < 0f || xLeft > canvas.width) continue
+                        if (yBottom < 0f || yTop > canvas.height) continue
+                        canvas.drawRect(xLeft, yTop, xRight, yBottom, markedPaint)
+                    }
+                }
             }
         }
 
@@ -414,12 +443,15 @@ class MaidenheadGridOverlay : Overlay() {
                 if (xRight < 0f || xLeft > canvas.width) continue
                 val label = cellLabel(lat, lon, zoom)
                 if (showFirstCallLabels) {
-                    // 首通呼号模式: 只有绿格(worked)标注该格第一个通联的呼号,
-                    // 非绿格空着不写网格字符.
-                    if (label in workedGrids) {
-                        firstCallsByGrid[label]?.let { call ->
+                    // 首通呼号模式: 绿格(worked)标注该格第一个通联的呼号, 红格(marked)
+                    // 标注用户标记想通联的呼号, 均淡黄文字; 其它格空着不写网格字符.
+                    when {
+                        label in workedGrids -> firstCallsByGrid[label]?.let { call ->
                             canvas.drawText(call, (xLeft + xRight) / 2f, yCenter, firstCallPaint)
                         }
+                        label in markedGrids -> markedGrids[label]?.let { station ->
+                            canvas.drawText(station.call, (xLeft + xRight) / 2f, yCenter, firstCallPaint)
+                        }
                     }
                 } else {
                     canvas.drawText(label, (xLeft + xRight) / 2f, yCenter, labelPaint)

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapScreen.kt

@@ -362,7 +362,8 @@ private fun MapScreen(
                             centerOnStation = shouldCenter,
                             // 首通呼号标签只作用于 VUCC 视图(用户要求); "All"/其他奖状不过滤.
                             showFirstCallLabels = uiState.showFirstCallLabels && selectedAward == AwardType.VUCC,
-                            firstCallsByGrid = firstCallsByGrid
+                            firstCallsByGrid = firstCallsByGrid,
+                            markedGrids = uiState.markedGrids
                         )
                         if (!shouldCenter || uiState.stationPosition != null) {
                             prevGridMode = uiState.isGridMode
@@ -422,15 +423,19 @@ private fun MapScreen(
         }
     }
     // Centered dialog listing the tapped worked grid's confirmed satellite QSOs.
-    // Dismissed by tapping outside (no explicit close button).
+    // Dismissed by tapping outside (no explicit close button). Unworked grids
+    // open the same dialog with an empty list plus a mark-a-station reminder.
     selectedGrid?.let { grid ->
         WorkedGridQsoDialog(
             grid = grid,
             qsos = uiState.workedGridQsos[grid].orEmpty().sortedBy { it.epochMs },
+            marked = uiState.markedGrids[grid],
             isUtc = uiState.isUtc,
             matchCalculating = matchCalculating,
             onDismiss = { selectedGrid = null },
-            onMatch = { onMatchGrid(grid) }
+            onMatch = { onMatchGrid(grid) },
+            onMark = { call -> onAction(MapAction.SetMarkedStation(grid, call)) },
+            onRemoveMark = { onAction(MapAction.RemoveMarkedStation(grid)) }
         )
     }
 }
@@ -441,11 +446,16 @@ private fun MapScreen(
 private fun WorkedGridQsoDialog(
     grid: String,
     qsos: List<com.rtbishop.look4sat.core.domain.model.GridQso>,
+    marked: com.rtbishop.look4sat.core.domain.model.MarkedStation?,
     isUtc: Boolean,
     matchCalculating: Boolean,
     onDismiss: () -> Unit,
-    onMatch: () -> Unit
+    onMatch: () -> Unit,
+    onMark: (String) -> Unit,
+    onRemoveMark: () -> Unit
 ) {
+    var showMarkInput by remember { mutableStateOf(false) }
+    var callInput by remember { mutableStateOf("") }
     androidx.compose.ui.window.Dialog(onDismissRequest = onDismiss) {
         // Centered card, ~85% width, internal scroll for long lists.
         Card(
@@ -497,26 +507,127 @@ private fun WorkedGridQsoDialog(
                     }
                 }
                 androidx.compose.material3.HorizontalDivider()
-                if (qsos.isNotEmpty()) {
-                    // Group by callsign preserving first-contact order (list is
-                    // already sorted oldest-first); expandable rows.
-                    val grouped = remember(qsos) {
-                        qsos.groupBy { it.call }.entries.sortedBy { it.value.first().epochMs }
+                Column(
+                    Modifier
+                        .heightIn(max = 380.dp)
+                        .verticalScroll(rememberScrollState())
+                ) {
+                    // A marked station shows first as a red reminder row: red
+                    // callsign, "标记" in the count column, the marking date in
+                    // the date column, and a small delete icon to remove it.
+                    if (marked != null) {
+                        MarkedStationRow(marked = marked, isUtc = isUtc, onRemoveMark = onRemoveMark)
+                        androidx.compose.material3.HorizontalDivider(color = MaterialTheme.colorScheme.outlineVariant.copy(alpha = 0.3f))
                     }
-                    Column(
-                        Modifier
-                            .heightIn(max = 380.dp)
-                            .verticalScroll(rememberScrollState())
-                    ) {
+                    if (qsos.isNotEmpty()) {
+                        // Group by callsign preserving first-contact order (list is
+                        // already sorted oldest-first); expandable rows.
+                        val grouped = remember(qsos) {
+                            qsos.groupBy { it.call }.entries.sortedBy { it.value.first().epochMs }
+                        }
                         grouped.forEach { (call, callQsos) ->
                             WorkedGridCallRow(call, callQsos = callQsos, isUtc = isUtc)
                             androidx.compose.material3.HorizontalDivider(color = MaterialTheme.colorScheme.outlineVariant.copy(alpha = 0.3f))
                         }
                     }
+                    // Unworked grids: offer to mark a station the user wants to
+                    // contact in this grid (a reminder, cleared when worked).
+                    if (qsos.isEmpty()) {
+                        TextButton(
+                            onClick = {
+                                callInput = marked?.call.orEmpty()
+                                showMarkInput = true
+                            },
+                            modifier = Modifier.fillMaxWidth()
+                        ) {
+                            Icon(
+                                painter = painterResource(R.drawable.ic_add),
+                                contentDescription = null,
+                                modifier = Modifier.size(18.dp)
+                            )
+                            Spacer(Modifier.width(4.dp))
+                            Text(stringResource(R.string.grid_mark_station))
+                        }
+                    }
                 }
             }
         }
     }
+    // Mark-a-station input dialog: enter a callsign as a reminder.
+    if (showMarkInput) {
+        androidx.compose.material3.AlertDialog(
+            onDismissRequest = { showMarkInput = false },
+            title = { Text(stringResource(R.string.grid_mark_station)) },
+            text = {
+                androidx.compose.material3.OutlinedTextField(
+                    value = callInput,
+                    onValueChange = { callInput = it },
+                    label = { Text(stringResource(R.string.grid_mark_callsign)) },
+                    singleLine = true
+                )
+            },
+            confirmButton = {
+                TextButton(
+                    enabled = callInput.isNotBlank(),
+                    onClick = {
+                        onMark(callInput)
+                        showMarkInput = false
+                    }
+                ) { Text(stringResource(R.string.grid_mark_confirm)) }
+            },
+            dismissButton = {
+                TextButton(onClick = { showMarkInput = false }) { Text(stringResource(R.string.btn_cancel)) }
+            }
+        )
+    }
+}
+
+@Composable
+private fun MarkedStationRow(
+    marked: com.rtbishop.look4sat.core.domain.model.MarkedStation,
+    isUtc: Boolean,
+    onRemoveMark: () -> Unit
+) {
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp, vertical = 8.dp)
+    ) {
+        Text(
+            text = marked.call,
+            style = MaterialTheme.typography.titleMedium,
+            fontFamily = androidx.compose.ui.text.font.FontFamily.Monospace,
+            color = ComposeColor(0xFFFF3B30),
+            maxLines = 1,
+            overflow = androidx.compose.ui.text.style.TextOverflow.Ellipsis,
+            modifier = Modifier.weight(1f)
+        )
+        Text(
+            text = stringResource(R.string.grid_mark_label),
+            style = MaterialTheme.typography.bodySmall,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            textAlign = androidx.compose.ui.text.style.TextAlign.Center,
+            modifier = Modifier.weight(1f)
+        )
+        Row(
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.End,
+            modifier = Modifier.weight(1f)
+        ) {
+            Text(
+                text = formatDate(marked.epochMs, isUtc),
+                style = MaterialTheme.typography.bodySmall,
+                color = MaterialTheme.colorScheme.onSurfaceVariant
+            )
+            Icon(
+                painter = painterResource(R.drawable.ic_delete),
+                contentDescription = stringResource(R.string.grid_mark_delete),
+                tint = MaterialTheme.colorScheme.error,
+                modifier = Modifier
+                    .size(18.dp)
+                    .clickable(onClick = onRemoveMark)
+            )
+        }
+    }
 }
 
 @Composable
@@ -944,7 +1055,8 @@ private fun setGridMode(
     stationPosition: GeoPos?,
     centerOnStation: Boolean = false,
     showFirstCallLabels: Boolean = false,
-    firstCallsByGrid: Map<String, String> = emptyMap()
+    firstCallsByGrid: Map<String, String> = emptyMap(),
+    markedGrids: Map<String, com.rtbishop.look4sat.core.domain.model.MarkedStation> = emptyMap()
 ) {
     try {
         val gridOverlay = mapView.overlays[OVERLAY_GRID]
@@ -955,6 +1067,7 @@ private fun setGridMode(
             // 首通呼号模式: 绿格标注第一个通联的呼号, 非绿格不显示标签.
             gridOverlay.showFirstCallLabels = showFirstCallLabels
             gridOverlay.firstCallsByGrid = firstCallsByGrid
+            gridOverlay.markedGrids = markedGrids
             // ownGrid must be set on EVERY update — the position is available
             // regardless of whether this frame centers (centering happens only
             // on entry, but passing null here would wipe the bold outline).
@@ -966,6 +1079,7 @@ private fun setGridMode(
                 this.roamedGrids = roamedGrids
                 this.showFirstCallLabels = showFirstCallLabels
                 this.firstCallsByGrid = firstCallsByGrid
+                this.markedGrids = markedGrids
                 this.ownGrid = ownGridOf(stationPosition)
             }
         }

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapState.kt

@@ -34,6 +34,8 @@ data class MapState(
     val workedGridQsos: Map<String, List<com.rtbishop.look4sat.core.domain.model.GridQso>> = emptyMap(),
     /** 4-char gridsquares the station operated from (LoTW MY_GRIDSQUARE) — blue stripes. */
     val roamedGrids: Set<String> = emptySet(),
+    /** Stations the user marked in unworked gridsquares (grid -> mark) — red fill. */
+    val markedGrids: Map<String, com.rtbishop.look4sat.core.domain.model.MarkedStation> = emptyMap(),
     val stationPosition: GeoPos? = null,
     val orbitalPass: OrbitalPass,
     val track: List<List<GeoPos>>? = null,
@@ -52,6 +54,8 @@ sealed interface MapAction {
     data class SelectDefaultItem(val catnum: Int) : MapAction
     data class ToggleGridMode(val value: Boolean) : MapAction
     data class ToggleFirstCallLabels(val value: Boolean) : MapAction
+    data class SetMarkedStation(val grid: String, val call: String) : MapAction
+    data class RemoveMarkedStation(val grid: String) : MapAction
     data class SetVisible(val isVisible: Boolean) : MapAction
 }
 

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapViewModel.kt

@@ -90,11 +90,19 @@ class MapViewModel(
         }
         viewModelScope.launch {
             settingsRepo.wavelogSettings.collectLatest { _ ->
+                val workedGrids = settingsRepo.getWorkedGrids()
+                val markedGrids = settingsRepo.getMarkedGridStations()
+                // Marked stations auto-clear once their grid becomes worked:
+                // the reminder has served its purpose (user req: 网格变绿后标记自动清除).
+                val stale = markedGrids.keys.filter { it in workedGrids }
+                val activeMarks = if (stale.isEmpty()) markedGrids else markedGrids - stale.toSet()
+                if (stale.isNotEmpty()) settingsRepo.setMarkedGridStations(activeMarks)
                 _uiState.update {
                     it.copy(
-                        workedGrids = settingsRepo.getWorkedGrids(),
+                        workedGrids = workedGrids,
                         workedGridQsos = settingsRepo.getWorkedGridQsos(),
-                        roamedGrids = settingsRepo.getRoamedGrids()
+                        roamedGrids = settingsRepo.getRoamedGrids(),
+                        markedGrids = activeMarks
                     )
                 }
             }
@@ -112,6 +120,20 @@ class MapViewModel(
             is MapAction.SelectDefaultItem -> selectDefaultSatellite(action.catnum)
             is MapAction.ToggleGridMode -> settingsRepo.updateOtherSettings { it.copy(stateOfMapGrid = action.value) }
             is MapAction.ToggleFirstCallLabels -> settingsRepo.updateOtherSettings { it.copy(stateOfMapFirstCall = action.value) }
+            is MapAction.SetMarkedStation -> {
+                val updated = settingsRepo.getMarkedGridStations() +
+                    (action.grid to com.rtbishop.look4sat.core.domain.model.MarkedStation(
+                        call = action.call.trim().uppercase(),
+                        epochMs = System.currentTimeMillis()
+                    ))
+                settingsRepo.setMarkedGridStations(updated)
+                _uiState.update { it.copy(markedGrids = updated) }
+            }
+            is MapAction.RemoveMarkedStation -> {
+                val updated = settingsRepo.getMarkedGridStations() - action.grid
+                settingsRepo.setMarkedGridStations(updated)
+                _uiState.update { it.copy(markedGrids = updated) }
+            }
             is MapAction.SetVisible -> isScreenVisible.value = action.isVisible
         }
     }