feat(database): add database migration service and update seeding process

- Add DatabaseMigrationService to handle database schema migrations
- Include all_migrations.dart in the import list
- Update AppDependencies to initialize and run database migrations
- Modify the application startup process to apply migrations before seeding

Author: fulleni

lib/src/config/app_dependencies.dart

@@ -9,8 +9,10 @@ import 'package:flutter_news_app_api_server_full_source_code/src/config/environm
 import 'package:flutter_news_app_api_server_full_source_code/src/rbac/permission_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/auth_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/auth_token_service.dart';
+import 'package:flutter_news_app_api_server_full_source_code/src/database/migrations/all_migrations.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/country_query_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/dashboard_summary_service.dart';
+import 'package:flutter_news_app_api_server_full_source_code/src/services/database_migration_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/database_seeding_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/default_user_preference_limit_service.dart';
 import 'package:flutter_news_app_api_server_full_source_code/src/services/jwt_auth_token_service.dart';
@@ -63,6 +65,7 @@ class AppDependencies {
   late final EmailRepository emailRepository;
 
   // Services
+  late final DatabaseMigrationService databaseMigrationService;
   late final TokenBlacklistService tokenBlacklistService;
   late final AuthTokenService authTokenService;
   late final VerificationCodeStorageService verificationCodeStorageService;
@@ -92,15 +95,25 @@ class AppDependencies {
       await _mongoDbConnectionManager.init(EnvironmentConfig.databaseUrl);
       _log.info('MongoDB connection established.');
 
-      // 2. Seed Database
+      // 2. Initialize and Run Database Migrations
+      databaseMigrationService = DatabaseMigrationService(
+        db: _mongoDbConnectionManager.db,
+        log: Logger('DatabaseMigrationService'),
+        migrations: allMigrations, // From lib/src/database/migrations/all_migrations.dart
+      );
+      await databaseMigrationService.init();
+      _log.info('Database migrations applied.');
+
+      // 3. Seed Database
+      // This runs AFTER migrations to ensure the schema is up-to-date.
       final seedingService = DatabaseSeedingService(
         db: _mongoDbConnectionManager.db,
         log: Logger('DatabaseSeedingService'),
       );
       await seedingService.seedInitialData();
       _log.info('Database seeding complete.');
 
-      // 3. Initialize Data Clients (MongoDB implementation)
+      // 4. Initialize Data Clients (MongoDB implementation)
       final headlineClient = DataMongodb<Headline>(
         connectionManager: _mongoDbConnectionManager,
         modelName: 'headlines',