refresh method
Force a refresh of the room list and (in polling/manual modes)
pull new messages for any room that changed.
Wire to a global pull-to-refresh on the room list screen. Streaming
modes (auto, webSocketOnly, serverSentEventsOnly) are no-op
— the event stream already delivers updates as they happen, so
calling refresh() there is safe but redundant.
Implementation
@override
Future<void> refresh() async {}