add MarianumConnectQuery base and adopt it in list queries

lib/api/marianumconnect/queries/user_search/user_search.dart

@@ -1,30 +1,20 @@
-import 'package:dio/dio.dart';
-
-import '../../errors/marianumconnect_error.dart';
-import '../../marianumconnect_api.dart';
-import '../../marianumconnect_endpoint.dart';
+import '../../marianumconnect_query.dart';
 import 'user_search_response.dart';
 
 /// Searches active users (students, teachers, staff) via the MarianumConnect
 /// mobile API. Returns each match's Nextcloud username plus role, so the Talk
 /// search can start a direct chat and label results without hitting Nextcloud.
-class UserSearch {
-  final Dio _dio;
+class UserSearch extends MarianumConnectQuery {
+  UserSearch({super.dio});
 
-  UserSearch({Dio? dio}) : _dio = dio ?? MarianumConnectApi.dio();
-
-  Future<UserSearchResponse> run(String query) async {
-    try {
-      final response = await _dio.get<List<dynamic>>(
-        MarianumConnectEndpoint.resolve('users/search'),
-        queryParameters: {'q': query},
-      );
-      final list = response.data!
-          .map((e) => McUserSearchResult.fromJson(e as Map<String, dynamic>))
-          .toList();
-      return UserSearchResponse(result: list);
-    } on DioException catch (e) {
-      throw mapMarianumConnectError(e);
-    }
-  }
+  Future<UserSearchResponse> run(String query) => guard(() async {
+    final response = await dio.get<List<dynamic>>(
+      endpoint('users/search'),
+      queryParameters: {'q': query},
+    );
+    final list = response.data!
+        .map((e) => McUserSearchResult.fromJson(e as Map<String, dynamic>))
+        .toList();
+    return UserSearchResponse(result: list);
+  });
 }