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.

test/file_test.dart

@@ -1,4 +1,4 @@
-import 'package:fires_flutter/fileUtils.dart';
+import 'package:fires_flutter/file_utils.dart';
 import 'package:test/test.dart';
 
 void main() {
@@ -23,8 +23,8 @@ void main() {
   });
 
   test('test privacy English md page', () async {
-    final String answer = await getFileNameOfLang(dir: 'assets/pages', fileName: 'privacy', ext: 'md', lang: 'en');
+    final String answer = await getFileNameOfLang(
+        dir: 'assets/pages', fileName: 'privacy', ext: 'md', lang: 'en');
     expect(answer, 'assets/pages/privacy-en.md');
   });
-
 }