feat(map): keep award filter selection across page switches

The award chip (VUCC/DXCC/WAJA/...) now lives in an Activity-scoped
MapFilterViewModel instead of a per-composition remember, so switching
to another page and back keeps the last selection; it resets to VUCC
only once per process (cold start). Removes the effect that forced
VUCC on every grid-mode entry.

app/src/main/java/com/rtbishop/look4sat/MainScreen.kt

@@ -81,6 +81,7 @@ import com.rtbishop.look4sat.core.presentation.Screen
 import com.rtbishop.look4sat.core.presentation.hasEnoughHeight
 import com.rtbishop.look4sat.core.presentation.hasEnoughWidth
 import com.rtbishop.look4sat.feature.map.MapDestination
+import com.rtbishop.look4sat.feature.map.MapFilterViewModel
 import com.rtbishop.look4sat.feature.mutual.MutualScreen
 import com.rtbishop.look4sat.feature.mutual.MutualViewModel
 import com.rtbishop.look4sat.feature.passes.PassesDestination
@@ -169,6 +170,12 @@ fun MainScreen(
         viewModelStoreOwner = context as ViewModelStoreOwner,
         factory = MutualViewModel.factory(container)
     )
+    // Activity-scoped so the map's award filter survives page switches;
+    // resets to VUCC only on cold start (fresh process).
+    val mapFilterViewModel: MapFilterViewModel = viewModel(
+        viewModelStoreOwner = context as ViewModelStoreOwner,
+        factory = MapFilterViewModel.factory()
+    )
 
     CompositionLocalProvider(
         LocalElevationThresholds provides ElevationThresholds(
@@ -237,7 +244,7 @@ fun MainScreen(
                             )
                         }
                         entry<Screen.Map> {
-                            MapDestination()
+                            MapDestination(mapFilterViewModel = mapFilterViewModel)
                         }
                         entry<Screen.Mutual> {
                             MutualScreen(

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

@@ -0,0 +1,27 @@
+package com.rtbishop.look4sat.feature.map
+
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.mutableStateOf
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import com.rtbishop.look4sat.core.domain.model.AwardType
+
+/**
+ * Session-scoped holder for the map's award filter selection.
+ *
+ * Scoped to the Activity (not the navigation entry) so the selection survives
+ * switching to another page and back; it resets to VUCC only when the process
+ * starts fresh (cold start), which is what the user expects as the default.
+ */
+class MapFilterViewModel : ViewModel() {
+
+    /** Last chosen award chip; null means "All". Initialized to VUCC once per process. */
+    val selectedAward: MutableState<AwardType?> = mutableStateOf(AwardType.VUCC)
+
+    companion object {
+        fun factory() = viewModelFactory {
+            initializer { MapFilterViewModel() }
+        }
+    }
+}

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

@@ -144,7 +144,9 @@ private val moonIconPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
 }
 
 @Composable
-fun MapDestination() {
+fun MapDestination(
+    mapFilterViewModel: MapFilterViewModel
+) {
     val context = LocalContext.current
     val container = (context.applicationContext as IContainerProvider).getMainContainer()
     val viewModel: MapViewModel = viewModel(factory = MapViewModel.factory(container))
@@ -165,11 +167,16 @@ fun MapDestination() {
             viewModel.onAction(MapAction.SetVisible(false))
         }
     }
-    MapScreen(uiState, viewModel::onAction, mapView)
+    MapScreen(uiState, viewModel::onAction, mapView, mapFilterViewModel)
 }
 
 @Composable
-private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView: MapView) {
+private fun MapScreen(
+    uiState: MapState,
+    onAction: (MapAction) -> Unit,
+    mapView: MapView,
+    mapFilterViewModel: MapFilterViewModel
+) {
     val rotateMod = Modifier.rotate(180f)
     val timeString = uiState.mapData?.aosTime ?: "00:00:00"
     val isTimeAos = uiState.mapData?.isTimeAos ?: true
@@ -177,9 +184,9 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
     // Tapped worked grid -> centered QSO dialog. Local UI state: the map is the
     // only consumer and it resets when leaving the page.
     var selectedGrid by remember { mutableStateOf<String?>(null) }
-    // Selected award filter. Entering grid mode defaults to VUCC (the plain
+    // Selected award filter. Lives in an Activity-scoped ViewModel so it
-    // worked-grid view); the reset effect below re-asserts that on every entry.
+    // survives page switches; defaults to VUCC only once per process (cold start).
-    var selectedAward by remember { mutableStateOf<AwardType?>(AwardType.VUCC) }
+    var selectedAward by mapFilterViewModel.selectedAward
     // Six-award progress derived from the confirmed QSO store; recomputed when
     // the store changes (LoTW/Wavelog sync).
     // Per operated-grid VUCC breakdown: myGrid -> set of worked grids worked from it.
@@ -240,12 +247,6 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
         (mapView.overlays.getOrNull(OVERLAY_GRID) as? MaidenheadGridOverlay)?.selectedGrid = selectedGrid
         mapView.invalidate()
     }
-    // Re-assert the VUCC default each time grid mode is entered; while already
-    // in grid mode the user's chip choice is preserved.
-    LaunchedEffect(uiState.isGridMode) {
-        if (uiState.isGridMode) selectedAward = AwardType.VUCC
-    }
-
     LaunchedEffect(uiState.track) {
         // In grid mode the map is centered on the local grid square; following
         // the satellite subpoint here would override that centering on every