feat(07-02): add sort dropdown tests to HomeScreen and fix AppShell test regression

- Add sortPreferenceProvider override to _buildApp test helper
- Add 'HomeScreen sort dropdown' test group: verifies PopupMenuButton<TaskSortOption> and AppBar title
- Fix app_shell_test: expect findsWidgets for 'Übersicht' since AppBar title now also shows it
- 115 tests pass total (113 existing + 2 new)

test/features/home/presentation/home_screen_test.dart

@@ -10,6 +10,8 @@ import 'package:household_keeper/features/home/presentation/calendar_providers.d
 import 'package:household_keeper/features/rooms/presentation/room_providers.dart';
 import 'package:household_keeper/features/tasks/domain/effort_level.dart';
 import 'package:household_keeper/features/tasks/domain/frequency.dart';
+import 'package:household_keeper/features/tasks/domain/task_sort_option.dart';
+import 'package:household_keeper/features/tasks/presentation/sort_preference_notifier.dart';
 import 'package:household_keeper/l10n/app_localizations.dart';
 import 'package:household_keeper/features/home/domain/daily_plan_models.dart';
 
@@ -65,6 +67,7 @@ Widget _buildApp(CalendarDayState dayState) {
     roomWithStatsListProvider.overrideWith(
       (ref) => Stream.value([]),
     ),
+    sortPreferenceProvider.overrideWith(SortPreferenceNotifier.new),
   ]);
 
   return UncontrolledProviderScope(
@@ -238,4 +241,38 @@ void main() {
       expect(find.byType(ListView), findsWidgets);
     });
   });
+
+  group('HomeScreen sort dropdown', () {
+    testWidgets('shows sort dropdown in AppBar', (tester) async {
+      await tester.pumpWidget(_buildApp(CalendarDayState(
+        selectedDate: today,
+        dayTasks: const [],
+        overdueTasks: const [],
+        totalTaskCount: 0,
+      )));
+      await tester.pump();
+      await tester.pump(const Duration(milliseconds: 500));
+
+      // SortDropdown wraps a PopupMenuButton<TaskSortOption>
+      expect(
+        find.byType(PopupMenuButton<TaskSortOption>),
+        findsOneWidget,
+      );
+    });
+
+    testWidgets('shows AppBar with title', (tester) async {
+      await tester.pumpWidget(_buildApp(CalendarDayState(
+        selectedDate: today,
+        dayTasks: const [],
+        overdueTasks: const [],
+        totalTaskCount: 0,
+      )));
+      await tester.pump();
+      await tester.pump(const Duration(milliseconds: 500));
+
+      // tabHome l10n string is 'Übersicht'. It appears in the AppBar title
+      // and also in the bottom navigation bar label — use findsWidgets.
+      expect(find.text('\u00dcbersicht'), findsWidgets);
+    });
+  });
 }