feat(02-02): build rooms screen with reorderable card grid and room card

- Replace placeholder RoomsScreen with ConsumerWidget watching roomWithStatsProvider
- Create RoomCard with icon, name, due count badge, cleanliness progress bar
- 2-column ReorderableBuilder grid with drag-and-drop reorder
- Empty state, loading, error states with retry
- Long-press menu for edit/delete with confirmation dialog
- FAB for room creation navigation
- Update app_shell_test with provider override for rooms stream

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/shell/app_shell_test.dart

@@ -1,9 +1,11 @@
+// ignore_for_file: scoped_providers_should_specify_dependencies
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 import 'package:household_keeper/core/router/router.dart';
+import 'package:household_keeper/features/rooms/presentation/room_providers.dart';
 import 'package:household_keeper/l10n/app_localizations.dart';
 
 void main() {
@@ -12,18 +14,29 @@ void main() {
       SharedPreferences.setMockInitialValues({});
     });
 
-    testWidgets('renders 3 navigation destinations with correct German labels',
-        (tester) async {
-      await tester.pumpWidget(
-        ProviderScope(
-          child: MaterialApp.router(
-            routerConfig: router,
-            localizationsDelegates: AppLocalizations.localizationsDelegates,
-            supportedLocales: const [Locale('de')],
-            locale: const Locale('de'),
+    /// Helper to build the app with room provider overridden to empty list.
+    Widget buildApp() {
+      return ProviderScope(
+        overrides: [
+          // Override the stream provider to return an empty list immediately
+          // so that the rooms screen shows the empty state without needing a DB.
+          // ignore: scoped_providers_should_specify_dependencies
+          roomWithStatsListProvider.overrideWith(
+            (ref) => Stream.value([]),
           ),
+        ],
+        child: MaterialApp.router(
+          routerConfig: router,
+          localizationsDelegates: AppLocalizations.localizationsDelegates,
+          supportedLocales: const [Locale('de')],
+          locale: const Locale('de'),
         ),
       );
+    }
+
+    testWidgets('renders 3 navigation destinations with correct German labels',
+        (tester) async {
+      await tester.pumpWidget(buildApp());
       await tester.pumpAndSettle();
 
       // Verify 3 NavigationDestination widgets are rendered
@@ -37,16 +50,7 @@ void main() {
 
     testWidgets('tapping a destination changes the selected tab',
         (tester) async {
-      await tester.pumpWidget(
-        ProviderScope(
-          child: MaterialApp.router(
-            routerConfig: router,
-            localizationsDelegates: AppLocalizations.localizationsDelegates,
-            supportedLocales: const [Locale('de')],
-            locale: const Locale('de'),
-          ),
-        ),
-      );
+      await tester.pumpWidget(buildApp());
       await tester.pumpAndSettle();
 
       // Initially on Home tab (index 0) -- verify home empty state is shown
@@ -56,7 +60,7 @@ void main() {
       await tester.tap(find.text('R\u00e4ume'));
       await tester.pumpAndSettle();
 
-      // Verify we see Rooms content now
+      // Verify we see Rooms content now (empty state)
       expect(find.text('Hier ist noch alles leer!'), findsOneWidget);
 
       // Tap the Settings tab (third destination)