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

ios/Flutter/flutter_export_environment.sh

@@ -2,12 +2,12 @@
 # This is a generated file; do not edit or check into version control.
 export "FLUTTER_ROOT=/home/vjrj/bin/flutter"
 export "FLUTTER_APPLICATION_PATH=/home/vjrj/proyectos/git-sea/fires_flutter"
+export "COCOAPODS_PARALLEL_CODE_SIGN=true"
 export "FLUTTER_TARGET=lib/main.dart"
 export "FLUTTER_BUILD_DIR=build"
-export "SYMROOT=${SOURCE_ROOT}/../build/ios"
 export "FLUTTER_BUILD_NAME=1.0.0"
 export "FLUTTER_BUILD_NUMBER=1"
 export "DART_OBFUSCATION=false"
-export "TRACK_WIDGET_CREATION=false"
+export "TRACK_WIDGET_CREATION=true"
 export "TREE_SHAKE_ICONS=false"
-export "PACKAGE_CONFIG=.packages"
+export "PACKAGE_CONFIG=.dart_tool/package_config.json"