feat(save): persist daily-reward claim state

lib/data/save_repository.dart

@@ -56,6 +56,9 @@ class SaveRepository {
       for (final t in BoosterType.values) {
         _boosters[t] = boosters[t.name] as int? ?? 0;
       }
+      final daily = json['daily'] as Map<String, dynamic>?;
+      _dailyLastClaimedYmd = daily?['lastYmd'] as String?;
+      _dailyCalendarDay = daily?['day'] as int? ?? 0;
     }
   }
 
@@ -76,6 +79,8 @@ class SaveRepository {
   final Map<BoosterType, int> _boosters = {
     for (final t in BoosterType.values) t: 0,
   };
+  String? _dailyLastClaimedYmd;
+  int _dailyCalendarDay = 0;
 
   StreakState get streak => _streak;
   bool get tutorialDone => _tutorialDone;
@@ -133,6 +138,15 @@ class SaveRepository {
     return true;
   }
 
+  String? get dailyLastClaimedYmd => _dailyLastClaimedYmd;
+  int get dailyCalendarDay => _dailyCalendarDay;
+
+  Future<void> recordDailyClaim(String ymd, int day) {
+    _dailyLastClaimedYmd = ymd;
+    _dailyCalendarDay = day;
+    return _flush();
+  }
+
   Future<void> recordEndlessScore(int score) {
     if (score > _endlessBest) _endlessBest = score;
     return _flush();
@@ -210,6 +224,7 @@ class SaveRepository {
           },
           'endless': {'best': _endlessBest},
           'boosters': {for (final t in BoosterType.values) t.name: _boosters[t]},
+          'daily': {'lastYmd': _dailyLastClaimedYmd, 'day': _dailyCalendarDay},
         }),
       );
 }