add mention support

lib/controllers/rooms_controller.dart

@@ -0,0 +1,23 @@
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/client_controller.dart";
+import "package:nexus/helpers/extensions/get_full_room.dart";
+import "package:nexus/models/full_room.dart";
+
+class RoomsController extends AsyncNotifier<IList<FullRoom>> {
+  @override
+  Future<IList<FullRoom>> build() async {
+    final client = await ref.watch(ClientController.provider.future);
+
+    ref.onDispose(
+      client.onSync.stream.listen((_) => ref.invalidateSelf()).cancel,
+    );
+
+    return IList(await Future.wait(client.rooms.map((room) => room.fullRoom)));
+  }
+
+  static final provider =
+      AsyncNotifierProvider<RoomsController, IList<FullRoom>>(
+        RoomsController.new,
+      );
+}