updateMessage method
Implementation
@override
Future<ChatResult<void>> updateMessage(
String roomId,
ChatMessage message,
) async {
final messages = _messages[roomId];
if (messages == null) return const ChatSuccess(null);
final idx = messages.indexWhere((m) => m.id == message.id);
if (idx >= 0) {
messages[idx] = message;
}
return const ChatSuccess(null);
}