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>

test/ui/daily_reward_sheet_test.dart

@@ -0,0 +1,38 @@
+import 'package:block_seasons/l10n/gen/app_localizations.dart';
+import 'package:block_seasons/ui/widgets/daily_reward_sheet.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  Widget wrap(Widget child) => MaterialApp(
+        locale: const Locale('en'),
+        localizationsDelegates: AppLocalizations.localizationsDelegates,
+        supportedLocales: AppLocalizations.supportedLocales,
+        home: Scaffold(body: Center(child: child)),
+      );
+
+  testWidgets('renders 7 day cells with today highlighted', (tester) async {
+    await tester.pumpWidget(wrap(
+      DailyRewardSheet(day: 3, onClaim: (_) {}),
+    ));
+
+    for (var d = 1; d <= 7; d++) {
+      expect(find.byKey(ValueKey('daily_day_$d')), findsOneWidget,
+          reason: 'day $d cell');
+    }
+  });
+
+  testWidgets('claim and 2x buttons fire onClaim with the right flag',
+      (tester) async {
+    final claims = <bool>[];
+    await tester.pumpWidget(wrap(
+      DailyRewardSheet(day: 1, onClaim: claims.add),
+    ));
+
+    await tester.tap(find.byKey(const ValueKey('daily_claim')));
+    expect(claims, [false]);
+
+    await tester.tap(find.byKey(const ValueKey('daily_double')));
+    expect(claims, [false, true]);
+  });
+}