perf(database): optimize country search and indexing

- Replace text index with name-based index for countries collection
- Update index naming for improved clarity

Author: fulleni

lib/src/services/database_seeding_service.dart

@@ -118,10 +118,10 @@ class DatabaseSeedingService {
           .collection('sources')
           .createIndex(keys: {'name': 'text'}, name: 'sources_text_index');
 
-      // Text index for searching countries by name (case-insensitive)
+      // Index for searching countries by name (case-insensitive friendly)
       await _db
           .collection('countries')
-          .createIndex(keys: {'name': 'text'}, name: 'countries_text_index');
+          .createIndex(keys: {'name': 1}, name: 'countries_name_index');
 
       // Indexes for country aggregation queries
       await _db