feat: Add library directive to multiple BLoC and service files for improved organization

lib/blocs/group/group_bloc.dart

@@ -31,6 +31,7 @@
 ///   members: [member1, member2],
 /// ));
 /// ```
+library;
 import 'dart:async';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:travel_mate/services/error_service.dart';