feat(database): add local ads collection seeding and indexing

- Implement seeding for local ads collection
- Add index on 'adType' field for efficient querying
- Include necessary imports and fixtures for local ads

Author: fulleni

lib/src/services/database_seeding_service.dart

@@ -45,6 +45,13 @@ class DatabaseSeedingService {
       getId: (item) => item.id,
       toJson: (item) => item.toJson(),
     );
+    await _seedCollection<LocalAd>(
+      collectionName: 'local_ads',
+      fixtureData: localAdsFixturesData,
+      getId: (item) => (item as dynamic).id as String,
+      // ignore: unnecessary_lambdas
+      toJson: (item) => LocalAd.toJson(item),
+    );
 
     _log.info('Database seeding process completed.');
   }
@@ -131,6 +138,13 @@ class DatabaseSeedingService {
           .collection('countries')
           .createIndex(keys: {'name': 1}, name: 'countries_name_index');
 
+      /// Index for searching local ads by adType.
+      /// This index supports efficient queries and filtering on the 'adType' field
+      /// of local ad documents.
+      await _db
+          .collection('local_ads')
+          .createIndex(keys: {'adType': 1}, name: 'local_ads_adType_index');
+
       // --- TTL and Unique Indexes via runCommand ---
       // The following indexes are created using the generic `runCommand` because
       // they require specific options not exposed by the simpler `createIndex`