added clear message for denied camera or gallery access

test/api/errors/error_mapper_test.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:io';
 
 import 'package:dio/dio.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:http/http.dart' as http;
 import 'package:marianum_mobile/api/api_error.dart';
@@ -10,6 +11,7 @@ import 'package:marianum_mobile/api/errors/error_mapper.dart';
 import 'package:marianum_mobile/api/errors/network_exception.dart';
 import 'package:marianum_mobile/api/errors/not_found_exception.dart';
 import 'package:marianum_mobile/api/errors/parse_exception.dart';
+import 'package:marianum_mobile/api/errors/permission_exception.dart';
 import 'package:nextcloud/nextcloud.dart';
 
 void main() {
@@ -142,10 +144,7 @@ void main() {
 
     test('401 maps to the unauthorized AuthException', () {
       const ex = DynamiteApiException(401, {}, '');
-      expect(
-        errorToUserMessage(ex),
-        AuthException.unauthorized().userMessage,
-      );
+      expect(errorToUserMessage(ex), AuthException.unauthorized().userMessage);
       expect(errorAllowsRetry(ex), isFalse);
     });
 
@@ -205,4 +204,29 @@ void main() {
       expect(errorAllowsRetry(StateError('x')), isTrue);
     });
   });
+
+  group('PermissionException.fromPlatform', () {
+    test('camera_access_denied maps to the camera message', () {
+      final mapped = PermissionException.fromPlatform(
+        PlatformException(code: 'camera_access_denied', message: 'denied'),
+      );
+      expect(mapped?.userMessage, contains('Kamera'));
+      expect(mapped?.technicalDetails, 'denied');
+      expect(errorAllowsRetry(mapped), isFalse);
+    });
+
+    test('photo_access_denied maps to the photos message', () {
+      final mapped = PermissionException.fromPlatform(
+        PlatformException(code: 'photo_access_denied'),
+      );
+      expect(mapped?.userMessage, contains('Fotos'));
+    });
+
+    test('unrelated platform codes are not mapped', () {
+      expect(
+        PermissionException.fromPlatform(PlatformException(code: 'other')),
+        isNull,
+      );
+    });
+  });
 }