feat: Delete chat_box.dart and references (#287)

Author: jacobsimionato

packages/flutter_genui/lib/flutter_genui.dart

@@ -19,7 +19,6 @@ export 'src/core/widgets/chat_primitives.dart';
 export 'src/facade/ui_agent.dart';
 export 'src/model/catalog.dart';
 export 'src/model/catalog_item.dart';
-export 'src/model/chat_box.dart';
 export 'src/model/chat_message.dart';
 export 'src/model/ui_models.dart';
 export 'src/primitives/logging.dart';