Feat: Ersetzt die Isar-Datenbank durch die drift-Datenbank

lib/Services/database_service.dart

@@ -0,0 +1,16 @@
+import '../Entities/drift_database.dart';
+
+class DatabaseService {
+  factory DatabaseService() => _instance;
+
+  DatabaseService._internal();
+
+  static final DatabaseService _instance = DatabaseService._internal();
+
+  AppDatabase? _database;
+
+  AppDatabase get database {
+    _database ??= AppDatabase();
+    return _database!;
+  }
+}