feat(07-02): build SortDropdown widget and integrate into HomeScreen and TaskListScreen

- Create SortDropdown ConsumerWidget using PopupMenuButton<TaskSortOption>
- Displays current sort label with sort icon in AppBar actions
- Check mark shown on active option via Opacity widget
- Add Scaffold with AppBar (title: Übersicht, actions: SortDropdown) to HomeScreen
- Add SortDropdown before edit/delete IconButtons in TaskListScreen AppBar

lib/features/home/presentation/home_screen.dart

@@ -4,6 +4,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:household_keeper/features/home/presentation/calendar_day_list.dart';
 import 'package:household_keeper/features/home/presentation/calendar_providers.dart';
 import 'package:household_keeper/features/home/presentation/calendar_strip.dart';
+import 'package:household_keeper/features/tasks/presentation/sort_dropdown.dart';
 import 'package:household_keeper/l10n/app_localizations.dart';
 
 /// The app's primary screen: a horizontal calendar strip at the top with a
@@ -30,40 +31,46 @@ class _HomeScreenState extends ConsumerState<HomeScreen> {
   Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context);
 
-    return Stack(
-      children: [
-        Column(
-          children: [
-            CalendarStrip(
-              controller: _stripController,
-              onTodayVisibilityChanged: (visible) {
-                setState(() => _showTodayButton = !visible);
-              },
-            ),
-            const Expanded(child: CalendarDayList()),
-          ],
-        ),
-        if (_showTodayButton)
-          Positioned(
-            bottom: 16,
-            left: 0,
-            right: 0,
-            child: Center(
-              child: FloatingActionButton.extended(
-                onPressed: () {
-                  final now = DateTime.now();
-                  final today = DateTime(now.year, now.month, now.day);
-                  ref
-                      .read(selectedDateProvider.notifier)
-                      .selectDate(today);
-                  _stripController.scrollToToday();
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(l10n.tabHome),
+        actions: const [SortDropdown()],
+      ),
+      body: Stack(
+        children: [
+          Column(
+            children: [
+              CalendarStrip(
+                controller: _stripController,
+                onTodayVisibilityChanged: (visible) {
+                  setState(() => _showTodayButton = !visible);
                 },
-                icon: const Icon(Icons.today),
-                label: Text(l10n.calendarTodayButton),
+              ),
+              const Expanded(child: CalendarDayList()),
+            ],
+          ),
+          if (_showTodayButton)
+            Positioned(
+              bottom: 16,
+              left: 0,
+              right: 0,
+              child: Center(
+                child: FloatingActionButton.extended(
+                  onPressed: () {
+                    final now = DateTime.now();
+                    final today = DateTime(now.year, now.month, now.day);
+                    ref
+                        .read(selectedDateProvider.notifier)
+                        .selectDate(today);
+                    _stripController.scrollToToday();
+                  },
+                  icon: const Icon(Icons.today),
+                  label: Text(l10n.calendarTodayButton),
+                ),
               ),
             ),
-          ),
-      ],
+        ],
+      ),
     );
   }
 }

lib/features/tasks/presentation/sort_dropdown.dart

@@ -0,0 +1,71 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.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';
+
+/// A reusable sort dropdown widget for use in AppBar actions.
+///
+/// Displays the current sort option as a labelled button with a sort icon.
+/// Tapping opens a popup menu with three options: A–Z, Intervall, Aufwand.
+/// The active option is indicated with a visible check mark.
+///
+/// Reads sort state from [sortPreferenceProvider] and writes via
+/// [SortPreferenceNotifier.setSortOption].
+class SortDropdown extends ConsumerWidget {
+  const SortDropdown({super.key});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final current = ref.watch(sortPreferenceProvider);
+    final l10n = AppLocalizations.of(context);
+    final theme = Theme.of(context);
+
+    return PopupMenuButton<TaskSortOption>(
+      onSelected: (value) =>
+          ref.read(sortPreferenceProvider.notifier).setSortOption(value),
+      itemBuilder: (context) => TaskSortOption.values.map((option) {
+        final isSelected = option == current;
+        return PopupMenuItem<TaskSortOption>(
+          value: option,
+          child: Row(
+            children: [
+              Opacity(
+                opacity: isSelected ? 1.0 : 0.0,
+                child: const Icon(Icons.check, size: 18),
+              ),
+              const SizedBox(width: 8),
+              Text(_label(option, l10n)),
+            ],
+          ),
+        );
+      }).toList(),
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 8),
+        child: Row(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            const Icon(Icons.sort),
+            const SizedBox(width: 4),
+            Text(
+              _label(current, l10n),
+              style: theme.textTheme.labelLarge,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  String _label(TaskSortOption option, AppLocalizations l10n) {
+    switch (option) {
+      case TaskSortOption.alphabetical:
+        return l10n.sortAlphabetical;
+      case TaskSortOption.interval:
+        return l10n.sortInterval;
+      case TaskSortOption.effort:
+        return l10n.sortEffort;
+    }
+  }
+}

lib/features/tasks/presentation/task_list_screen.dart

@@ -4,6 +4,7 @@ import 'package:go_router/go_router.dart';
 
 import 'package:household_keeper/core/database/database.dart';
 import 'package:household_keeper/core/providers/database_provider.dart';
+import 'package:household_keeper/features/tasks/presentation/sort_dropdown.dart';
 import 'package:household_keeper/features/tasks/presentation/task_providers.dart';
 import 'package:household_keeper/features/tasks/presentation/task_row.dart';
 import 'package:household_keeper/l10n/app_localizations.dart';
@@ -27,6 +28,7 @@ class TaskListScreen extends ConsumerWidget {
       appBar: AppBar(
         title: _RoomTitle(roomId: roomId),
         actions: [
+          const SortDropdown(),
           IconButton(
             icon: const Icon(Icons.edit),
             onPressed: () => context.go('/rooms/$roomId/edit'),