fix: resolve 78 strict analysis errors with explicit type annotations

Implemented systematic type safety improvements across the codebase to eliminate all 78 strict analysis errors:

## Phase 1: Quick Wins (Redux & Model Fixes)
- Added explicit type annotations to Redux reducer parameters
- Fixed copyWith() methods in FireNotification and YourLocation models with proper nullable types
- Fixed BasicLocation field initializers with type casts (num to double)
- Fixed context parameter inference in IntroPage and PrivacyPage
- Regenerated .g.dart files with build_runner

## Phase 2: JSON Deserialization
- Fixed homePage.dart Firebase message parameter casting (9 errors)
- Fixed firesApi.dart JSON parsing:
  - Added explicit casts for num to double/int conversions
  - Fixed array iteration with proper List<dynamic> casting
  - Added return type annotation to objectIdFromJson()
  - Fixed nested JSON access in getMonitoredAreas()
- Fixed globalFiresBottomStats.dart dynamic to int/String casting
- Fixed locationUtils.dart string assignments

## Phase 3: Config & Redux Middleware
- Fixed mainCommon.dart config map access with explicit String casts
- Fixed mainProd.dart Sentry DSN casting
- Fixed fetchDataMiddleware.dart:
  - Added Store<AppState>, String type annotations to createUser()
  - Added Function(YourLocation) type to subscribeViaApi callback
  - Added Exception type to catchError handler
- Fixed fireMapReducer.dart restoreStatusAfterSave parameter type
- Fixed persist files with Map<String, dynamic> type annotations

## Phase 4: Edge Cases
- Fixed slider.dart method return types (Widget sizeText, Widget warningText)
- Fixed mainDrawer.dart Key? parameter type annotation

Result: 78 errors → 0 errors

lib/models/appState.g.dart

@@ -6,27 +6,31 @@ part of 'appState.dart';
 // JsonSerializableGenerator
 // **************************************************************************
 
-AppState _$AppStateFromJson(Map json) {
-  return $checkedNew('AppState', json, () {
-    final val = AppState(
-      yourLocations: $checkedConvert(
-          json,
-          'yourLocations',
-          (v) => (v as List)
-              .map((e) =>
-                  YourLocation.fromJson(Map<String, dynamic>.from(e as Map)))
-              .toList()),
-      fireNotifications: $checkedConvert(
-          json,
-          'fireNotifications',
-          (v) => (v as List)
-              .map((e) => FireNotification.fromJson(
-                  Map<String, dynamic>.from(e as Map)))
-              .toList()),
+AppState _$AppStateFromJson(Map json) => $checkedCreate(
+      'AppState',
+      json,
+      ($checkedConvert) {
+        final val = AppState(
+          yourLocations: $checkedConvert(
+              'yourLocations',
+              (v) =>
+                  (v as List<dynamic>?)
+                      ?.map((e) => YourLocation.fromJson(
+                          Map<String, dynamic>.from(e as Map)))
+                      .toList() ??
+                  const <YourLocation>[]),
+          fireNotifications: $checkedConvert(
+              'fireNotifications',
+              (v) =>
+                  (v as List<dynamic>?)
+                      ?.map((e) => FireNotification.fromJson(
+                          Map<String, dynamic>.from(e as Map)))
+                      .toList() ??
+                  const <FireNotification>[]),
+        );
+        return val;
+      },
     );
-    return val;
-  });
-}
 
 Map<String, dynamic> _$AppStateToJson(AppState instance) => <String, dynamic>{
       'yourLocations': instance.yourLocations.map((e) => e.toJson()).toList(),