added guardian login with views for their assigned childs

lib/widget/child_switcher.dart

@@ -0,0 +1,85 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_bloc/flutter_bloc.dart';
+
+import '../api/marianumconnect/queries/get_capabilities/guardian_child.dart';
+import '../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
+import '../state/app/modules/children/child_selection_cubit.dart';
+import '../utils/haptics.dart';
+import 'centered_leading.dart';
+import 'details_bottom_sheet.dart';
+import 'placeholder_view.dart';
+
+/// AppBar action that shows the selected child and lets a guardian switch to
+/// another one. Invisible unless there is a choice to make.
+class ChildSwitcher extends StatelessWidget {
+  const ChildSwitcher({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final children = context.watch<CapabilitiesCubit>().state.children;
+    if (children.length < 2) return const SizedBox.shrink();
+    final selected = effectiveChild(
+      children,
+      context.watch<ChildSelectionCubit>().state,
+    )!;
+    return TextButton.icon(
+      icon: const Icon(Icons.face_outlined),
+      label: Text(selected.firstName),
+      onPressed: () => _pick(context, selected.id),
+    );
+  }
+
+  void _pick(BuildContext context, String selectedId) {
+    final selection = context.read<ChildSelectionCubit>();
+    final children = context.read<CapabilitiesCubit>().state.children;
+    showDetailsBottomSheet(
+      context,
+      header: const ListTile(title: Text('Kind auswählen')),
+      children: (sheetContext) => [
+        for (final child in children)
+          ChildTile(
+            child: child,
+            trailing: child.id == selectedId ? const Icon(Icons.check) : null,
+            onTap: () {
+              Haptics.selection();
+              selection.select(child.id);
+              Navigator.pop(sheetContext);
+            },
+          ),
+      ],
+    );
+  }
+}
+
+/// One linked child: name and class.
+class ChildTile extends StatelessWidget {
+  final GuardianChild child;
+  final Widget? trailing;
+  final VoidCallback? onTap;
+
+  const ChildTile({required this.child, this.trailing, this.onTap, super.key});
+
+  @override
+  Widget build(BuildContext context) => ListTile(
+    leading: const CenteredLeading(Icon(Icons.face_outlined)),
+    title: Text(child.displayName),
+    subtitle: child.className.isEmpty
+        ? null
+        : Text('Klasse ${child.className}'),
+    trailing: trailing,
+    onTap: onTap,
+  );
+}
+
+/// Shown by per-child modules while a guardian has no linked child.
+class NoChildrenPlaceholder extends StatelessWidget {
+  const NoChildrenPlaceholder({super.key});
+
+  @override
+  Widget build(BuildContext context) => const PlaceholderView(
+    icon: Icons.family_restroom_outlined,
+    text:
+        'Deinem Konto ist noch kein Kind zugeordnet. Bitte wende dich an '
+        'das Sekretariat.',
+  );
+}

lib/widget/file_viewer/unknown_preview_block.dart

@@ -1,8 +1,8 @@
 import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 
-import '../../model/account_data.dart';
 import '../../model/endpoint_data.dart';
+import '../../session/session_manager.dart';
 import '../../share_intent/remote_file_ref.dart';
 import '../app_progress_indicator.dart';
 
@@ -67,7 +67,7 @@ class _UnknownPreviewBlockState extends State<UnknownPreviewBlock> {
       width: _previewSize,
       height: _previewSize,
       child: CachedNetworkImage(
-        httpHeaders: AccountData().authHeaders(),
+        httpHeaders: SessionManager().requireNextcloud().authHeaders,
         imageUrl: _ncPreviewUrl(remote, width: 360),
         fadeInDuration: Duration.zero,
         fadeOutDuration: Duration.zero,

lib/widget/user_avatar.dart

@@ -8,9 +8,9 @@ import 'package:flutter_svg/flutter_svg.dart';
 import 'package:http/http.dart' as http;
 
 import '../api/http_errors.dart';
-import '../model/account_data.dart';
 import '../model/endpoint_data.dart';
 import '../push/push_avatar.dart';
+import '../session/session_manager.dart';
 import 'a11y/a11y_labels.dart';
 import 'avatar_disk_cache.dart';
 
@@ -162,7 +162,7 @@ Future<AvatarPayload?> _fetchAvatarPayload(String url) async {
     () => http.get(
       Uri.parse(url),
       headers: {
-        ...AccountData().authHeaders(),
+        ...SessionManager().requireNextcloud().authHeaders,
         'Accept': 'image/png,image/jpeg,image/webp,image/svg+xml',
       },
     ),
@@ -368,7 +368,6 @@ class _UserAvatarState extends State<UserAvatar> {
     return listEquals(a.bytes, b.bytes);
   }
 
-
   @override
   Widget build(BuildContext context) {
     final radius = widget.size.toDouble();