added support for multiple accounts with an account switcher in settings

lib/api/marianumconnect/queries/auth_me/auth_me.dart

@@ -0,0 +1,40 @@
+import 'package:dio/dio.dart';
+
+import '../../../errors/auth_exception.dart';
+import '../../auth/token_storage.dart';
+import '../../marianumconnect_api.dart';
+import '../../marianumconnect_query.dart';
+import '../auth_login/auth_login_response.dart';
+
+/// Reads the user behind the stored bearer token, which also probes that the
+/// token is still accepted.
+///
+/// Bypasses the shared dio singleton so the auth interceptor does not react
+/// to the 401 this probe is meant to observe.
+class AuthMe extends MarianumConnectQuery {
+  final MarianumConnectTokenStorage _tokenStorage;
+
+  AuthMe({
+    MarianumConnectTokenStorage tokenStorage =
+        const MarianumConnectTokenStorage(),
+    Dio? dio,
+  }) : _tokenStorage = tokenStorage,
+       super(dio: dio ?? MarianumConnectApi.plainDio());
+
+  /// Throws [AuthException] when the token is missing or rejected.
+  Future<void> run() async {
+    await user();
+  }
+
+  /// The signed-in user (names, type). Throws like [run].
+  Future<AuthLoginUser> user() async {
+    final options = await _tokenStorage.requireBearerOptions('AuthMe');
+    return guard(() async {
+      final response = await dio.get<Map<String, dynamic>>(
+        endpoint('auth/me'),
+        options: options,
+      );
+      return AuthLoginUser.fromJson(response.data!);
+    });
+  }
+}