feat(ui): 7-day daily-reward popup on home

Presentational DailyRewardSheet (7 cells, today highlighted, reward icons
from the calendar table, claim + watch-ad-2x buttons). HomeScreen becomes a
ConsumerStatefulWidget that shows it once per mount via a post-frame guard;
the 2x path grants the doubled reward only if the rewarded ad was earned,
else the base reward. Guards the throwing saveRepositoryProvider default so
a repo-less mount is a no-op.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/ui/screens/home_screen.dart

@@ -6,6 +6,7 @@ import '../../game/models/stage.dart';
 import '../../l10n/gen/app_localizations.dart';
 import '../../state/providers.dart';
 import '../widgets/banner_ad_slot.dart';
+import '../widgets/daily_reward_sheet.dart';
 import '../widgets/fade_route.dart';
 import '../widgets/pressable_scale.dart';
 import '../widgets/season_background.dart';
@@ -13,9 +14,14 @@ import 'game_screen.dart';
 import 'season_map_screen.dart';
 import 'settings_screen.dart';
 
-class HomeScreen extends ConsumerWidget {
+class HomeScreen extends ConsumerStatefulWidget {
   const HomeScreen({super.key});
 
+  @override
+  ConsumerState<HomeScreen> createState() => _HomeScreenState();
+}
+
+class _HomeScreenState extends ConsumerState<HomeScreen> {
   static const _logoColors = [
     Color(0xFFFF7EB3),
     Color(0xFFFFD166),
@@ -23,8 +29,52 @@ class HomeScreen extends ConsumerWidget {
     Color(0xFF7EDB9C),
   ];
 
+  bool _dailyChecked = false;
+
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) => _maybeShowDailyReward());
+  }
+
+  /// Once per home mount, surface the 7-day login reward if it is claimable
+  /// today. Guards the deliberately-throwing [saveRepositoryProvider] default
+  /// so a repo-less mount (e.g. a widget test) is a no-op rather than a crash.
+  void _maybeShowDailyReward() {
+    if (_dailyChecked || !mounted) return;
+    _dailyChecked = true;
+    try {
+      ref.read(saveRepositoryProvider);
+    } catch (_) {
+      return;
+    }
+    final daily = ref.read(dailyRewardProvider);
+    if (!daily.claimable) return;
+
+    showDialog<void>(
+      context: context,
+      builder: (dialogContext) => Dialog(
+        child: DailyRewardSheet(
+          day: daily.day,
+          onClaim: (doubled) async {
+            final notifier = ref.read(dailyRewardProvider.notifier);
+            if (doubled) {
+              // Watch an ad to double; if no ad was earned the base reward is
+              // still granted so the player is never left empty-handed.
+              final earned = await ref.read(adServiceProvider).showRewarded();
+              await notifier.claim(doubled: earned);
+            } else {
+              await notifier.claim();
+            }
+            if (dialogContext.mounted) Navigator.of(dialogContext).pop();
+          },
+        ),
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context)!;
     final streak = ref.watch(streakProvider);
     final best = ref.watch(endlessBestProvider);