Fix 13 lint issues: immutability, imports, async/await, and code style

High-priority fixes (10 issues):
- assignment_to_final errors (7): Use copyWith() to respect immutability in YourLocation, active_fires.dart, generic_map.dart, location_utils.dart, and fetch_data_middleware.dart instead of direct assignment
- Fixed import paths (3): Updated falsePositiveTypes.dart → false_positive_types.dart and firesApi.dart → fires_api.dart in reducers.dart, fire_notification_actions.dart, fires_api.dart

Medium/Low priority fixes (3 issues):
- unnecessary_non_null_assertion: Removed redundant '!' in app_intro_page.dart line 54
- use_super_parameters: Updated app_intro_page.dart to use modern super(key: key) syntax
- no_logic_in_create_state: Fixed material_app_with_intro.dart by moving parameters to State instead of createState
- noop_primitive_operations: Removed redundant .toString() in string interpolation
- avoid_void_async: Changed void _selectLocation to Future<void> in places_autocomplete_utils.dart
- avoid_dynamic_calls: Fixed dynamic map access in fires_api.dart by properly casting intermediate values

Result: Reduced lint issues from 56 to 20 (all remaining are by-design: library_private_types_in_public_api and implementation_imports from external packages)
APK builds successfully with no errors.

lib/generic_map.dart

@@ -99,12 +99,12 @@ class GenericMapState extends State<GenericMap> {
                 store.dispatch(SubscribeAction());
               },
               onSubsConfirmed: (YourLocation loc) {
-                loc.subscribed = true;
-                store.dispatch(SubscribeConfirmAction(loc));
+                store.dispatch(
+                    SubscribeConfirmAction(loc.copyWith(subscribed: true)));
               },
               onUnSubs: (YourLocation loc) {
-                loc.subscribed = false;
-                store.dispatch(UnSubscribeAction(loc));
+                store.dispatch(
+                    UnSubscribeAction(loc.copyWith(subscribed: false)));
               },
               onSlide: (YourLocation loc) {
                 store.dispatch(UpdateYourLocationMapAction(loc));
@@ -348,7 +348,8 @@ class GenericMapState extends State<GenericMap> {
                                               _location?.distance ?? 0,
                                           onSlide: (int distance) {
                                             if (_location != null) {
-                                              _location!.distance = distance;
+                                              _location = _location!
+                                                  .copyWith(distance: distance);
                                               view.onSlide(_location!);
                                             }
                                           })