added guardian login with views for their assigned childs

lib/view/pages/files/widgets/file_leading.dart

@@ -2,8 +2,8 @@ import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 
 import '../../../../api/marianumcloud/webdav/queries/list_files/cacheable_file.dart';
-import '../../../../model/account_data.dart';
 import '../../../../model/endpoint_data.dart';
+import '../../../../session/session_manager.dart';
 import '../data/file_type_icon.dart';
 
 /// Leading slot for a file row: shows the Nextcloud thumbnail when the
@@ -35,7 +35,7 @@ class FileLeading extends StatelessWidget {
                     'https://${EndpointData().nextcloud().full()}'
                     '/index.php/core/preview'
                     '?fileId=$fileId&x=128&y=128&a=0',
-                httpHeaders: AccountData().authHeaders(),
+                httpHeaders: SessionManager().requireNextcloud().authHeaders,
                 fit: BoxFit.cover,
                 fadeInDuration: Duration.zero,
                 fadeOutDuration: Duration.zero,