implemented global user search integration for Talk chats with role-coded badges and direct chat creation logic

lib/api/demo/demo_marianumconnect.dart

@@ -1,6 +1,7 @@
 import 'data/demo_breaker.dart';
 import 'data/demo_holidays.dart';
 import 'data/demo_timetable.dart';
+import 'data/demo_users.dart';
 
 /// Single source of truth for the MarianumConnect demo responses. The demo
 /// interceptor asks this for the body of any MC request. Read endpoints reuse
@@ -32,6 +33,10 @@ class DemoMarianumConnect {
         return DemoTimetable.holidays().result.map((e) => e.toJson()).toList();
       case 'holidays':
         return DemoHolidays.upcoming().map((e) => e.toJson()).toList();
+      case 'users/search':
+        return DemoUsers.search(query['q']?.toString() ?? '')
+            .map((e) => e.toJson())
+            .toList();
       case 'breaker':
         return DemoBreaker.none().toJson();
       case 'timetable/elements/teachers':