simplified code across the app and consolidated duplicated helpers

lib/view/pages/talk/search_chat.dart

@@ -11,7 +11,7 @@ import 'widgets/chat_tile.dart';
 import 'widgets/user_search_tile.dart';
 
 class SearchChat extends SearchDelegate<GetRoomResponseObject?> {
-  List<GetRoomResponseObject> chats;
+  final List<GetRoomResponseObject> chats;
   final void Function(GetRoomResponseObject room)? onTapOverride;
 
   /// When set, results are extended with a clearly separated "start a new chat"
@@ -145,8 +145,8 @@ class _SearchChatResultsState extends State<_SearchChatResults> {
         widget.chats
             .where(
               (e) =>
-                  e.displayName.toString().toLowerCase().contains(query) ||
-                  e.name.toString().toLowerCase().contains(query),
+                  e.displayName.toLowerCase().contains(query) ||
+                  e.name.toLowerCase().contains(query),
             )
             .toList()
           ..sort((a, b) => b.lastActivity.compareTo(a.lastActivity));