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

lib/blocs/message/message_bloc.dart

@@ -39,6 +39,7 @@
 ///   reaction: '👍',
 /// ));
 /// ```
+library;
 import 'dart:async';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import '../../models/message.dart';