feat(gridfinder): VUCC 网格寻线实地导航 + LoTW 上传台址预填联动 + 移除地图入口

- GridGeometry 网格线/点几何 + QthConverter grid4/grid8；golden vectors 单测
- 独立定位流 ILocationRepo/LocationRepo（stop 时 removeUpdates），不自动写台址
- feature/gridfinder 模块：罗盘表盘、极坐标近距图、线上/点上精度门控（连续 3 次 ≤6.1m）
- 「设为 LoTW 上传台址」：跳证书配置页并预填当前网格（1/2/4 格），只改台站 grid 字段
- 地图页入口移除，设置页单入口；顶部间距改 ScreenColumn 结构（与设置页同构）
- 术语统一「最近网格点」（中英）

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/LoTWUploadConfigDialog.kt

@@ -93,6 +93,7 @@ fun LoTWUploadConfigDialog(
     busy: Boolean,
     error: LoTWUploadError?,
     errorDetail: String = "",
+    initialGrid: String = "",
     onDismiss: () -> Unit,
     onImport: (ByteArray, CharArray) -> Unit,
     onRemove: () -> Unit,
@@ -100,7 +101,9 @@ fun LoTWUploadConfigDialog(
 ) {
     var password by remember { mutableStateOf("") }
     var selectedFile by remember { mutableStateOf<Uri?>(null) }
-    var grid by remember { mutableStateOf(station?.grid.orEmpty()) }
+    // A grid Finder prefill (e.g. "OL62,OL72" for a line, four grids for a
+    // corner) wins over the saved station grid; otherwise keep what TQSL had.
+    var grid by remember { mutableStateOf(initialGrid.ifBlank { station?.grid.orEmpty() }) }
     var cqZone by remember { mutableStateOf(station?.cqZone.orEmpty()) }
     var ituZone by remember { mutableStateOf(station?.ituZone.orEmpty()) }
     var iota by remember { mutableStateOf(station?.iota.orEmpty()) }

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/LoTWUploadDestination.kt

@@ -0,0 +1,71 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.feature.settings
+
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.lifecycle.viewmodel.compose.viewModel
+import com.rtbishop.look4sat.core.domain.repository.IContainerProvider
+
+/**
+ * Full-screen LoTW upload certificate + station location page.
+ *
+ * Reached from the Grid Finder's "Set as LoTW station location" button: the
+ * grids the operator currently stands on (1 inside, 2 on a line, 4 on a corner)
+ * are dropped into [container.pendingLoTWStationGrid] and consumed here as the
+ * station grid prefill, so the next upload stamps those VUCC squares instead of
+ * the certificate's home grid.
+ */
+@Composable
+fun LoTWUploadDestination(navigateUp: () -> Unit) {
+    val context = LocalContext.current
+    val container = (context.applicationContext as IContainerProvider).getMainContainer()
+    val viewModel: SettingsViewModel = viewModel(factory = SettingsViewModel.factory(container, context))
+    val uiState by viewModel.uiState.collectAsStateWithLifecycle()
+
+    // Consume the prefill once; re-entering the page later keeps the saved grid.
+    val initialGrid = container.pendingLoTWStationGrid.value.orEmpty()
+    LaunchedEffect(Unit) {
+        container.setPendingLoTWStationGrid(null)
+    }
+
+    Surface(modifier = Modifier.fillMaxSize(), color = MaterialTheme.colorScheme.background) {
+        LoTWUploadConfigDialog(
+            certificate = uiState.lotwCertificate,
+            station = uiState.lotwStation,
+            stationMeta = uiState.lotwStationMeta,
+            busy = uiState.lotwUploadBusy,
+            error = uiState.lotwUploadError,
+            errorDetail = uiState.lotwUploadErrorDetail,
+            initialGrid = initialGrid,
+            onDismiss = navigateUp,
+            onImport = { bytes, password ->
+                viewModel.onAction(SettingsAction.ImportLoTWCertificate(bytes, password))
+            },
+            onRemove = { viewModel.onAction(SettingsAction.RemoveLoTWCertificate) },
+            onSaveStation = { viewModel.onAction(SettingsAction.SaveLoTWStation(it)) }
+        )
+    }
+}

feature/settings/src/main/java/com/rtbishop/look4sat/feature/settings/SettingsScreen.kt

@@ -89,16 +89,20 @@ import java.util.Date
 import java.util.Locale
 
 @Composable
-fun SettingsDestination() {
+fun SettingsDestination(onOpenGridFinder: () -> Unit = {}) {
     val context = LocalContext.current
     val container = (context.applicationContext as IContainerProvider).getMainContainer()
     val viewModel: SettingsViewModel = viewModel(factory = SettingsViewModel.factory(container, context))
     val uiState by viewModel.uiState.collectAsStateWithLifecycle()
-    SettingsScreen(uiState, viewModel::onAction)
+    SettingsScreen(uiState, viewModel::onAction, onOpenGridFinder)
 }
 
 @Composable
-private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) -> Unit) {
+private fun SettingsScreen(
+    uiState: SettingsState,
+    onAction: (SettingsAction) -> Unit,
+    onOpenGridFinder: () -> Unit
+) {
     var showUpdateChecker by rememberSaveable { mutableStateOf(false) }
     var showMapSettings by rememberSaveable { mutableStateOf(false) }
     var showProjectWiki by rememberSaveable { mutableStateOf(false) }
@@ -378,6 +382,7 @@ private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) ->
                     showPosDialog = { dialogs.position = true },
                     showLocDialog = { dialogs.locator = true },
                     dismissPosMessage = { onAction(SettingsAction.DismissPosMessages) },
+                    openGridFinder = onOpenGridFinder,
                     onAction = onAction
                 )
             }
@@ -443,7 +448,7 @@ private fun SettingsScreen(uiState: SettingsState, onAction: (SettingsAction) ->
 private fun LocationCardPreview() = MainTheme {
     val stationPos = GeoPos(0.0, 0.0, 0.0, "IO91vl", 0L)
     val settings = PositionSettings(true, stationPos, 0)
-    LocationCard(settings = settings, setGpsPos = {}, showPosDialog = {}, {}, {}) {}
+    LocationCard(settings = settings, setGpsPos = {}, showPosDialog = {}, {}, {}, {}) {}
 }
 
 @Composable
@@ -453,6 +458,7 @@ private fun LocationCard(
     showPosDialog: () -> Unit,
     showLocDialog: () -> Unit,
     dismissPosMessage: () -> Unit,
+    openGridFinder: () -> Unit,
     onAction: (SettingsAction) -> Unit
 ) {
     ElevatedCard(modifier = Modifier.fillMaxWidth()) {
@@ -495,6 +501,12 @@ private fun LocationCard(
                     modifier = Modifier.weight(1f)
                 )
             }
+            Spacer(modifier = Modifier.height(4.dp))
+            CardButton(
+                onClick = openGridFinder,
+                text = stringResource(id = R.string.gridfinder_title),
+                modifier = Modifier.fillMaxWidth()
+            )
         }
     }
     if (settings.messageResId != 0) {