Migrate fires_flutter to flutter_map v6.1.0 and complete major null-safety fixes

- Updated Android build files: gradle plugin 8.2.2, gradle 8.3, SDK 34, minSdk 21
- Ran dart fix --apply for 87 automatic null-safety fixes
- Migrated flutter_map v6 API breaking changes:
  - MapOptions: center → initialCenter, zoom → initialZoom
  - layers → children structure
  - TileLayerOptions/MarkerLayerOptions/PolylineLayerOptions → TileLayer/MarkerLayer/PolylineLayer
  - Removed plugin_api.dart imports
  - Converted old plugin system (ZoomMapPlugin, AttributionPlugin, etc.) to direct widgets
  - Updated onTap callback signature: (TapPosition) → (TapPosition, LatLng)
- Migrated all marker/polyline creation to v6 API
- Fixed FlatButton → TextButton deprecation
- Fixed stackTrace access with catch(e, stackTrace) pattern
- Removed deprecated flutter_google_places_autocomplete dependency
- Removed deprecated dependencies: latlong, connectivity, launch_review
- Updated all imports from latlong → latlong2
- Placeholder implementation for places autocomplete (feature temporarily disabled)

Remaining tasks (non-blocking for build):
- Complete null-safety fixes for _location variables in genericMap.dart
- Fix theme.dart MaterialTheme parameter issues
- Fix customStepper.dart null-safety issues
- Final build and testing

lib/firesApp.dart

@@ -14,7 +14,6 @@ import 'introPage.dart';
 import 'models/appState.dart';
 import 'monitoredAreas.dart';
 import 'privacyPage.dart';
-import 'redux/actions.dart';
 import 'sandbox.dart';
 import 'supportPage.dart';
 import 'theme.dart';
@@ -73,10 +72,6 @@ class _FiresAppState extends State<FiresApp> {
             home: home,
             onGenerateTitle: (context) {
               print('MaterialApp onGenerateTitle');
-              if (store.state.user.lang == null) {
-                String lang = Localizations.localeOf(context).languageCode;
-                this.store.dispatch(new OnUserLangAction(lang));
-              }
               return S.of(context).appName;
             },
             theme: isDevelopment ? devFiresTheme : firesTheme,