Show cached schedule coverage status in admin

test/widget_test.dart

@@ -2,6 +2,7 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:jamshalat_masjid_screen/core/enums.dart';
 import 'package:jamshalat_masjid_screen/data/local/models.dart';
 import 'package:jamshalat_masjid_screen/data/services/hijri_service.dart';
+import 'package:jamshalat_masjid_screen/data/services/sync_service.dart';
 
 void main() {
   group('PrayerName display labels', () {
@@ -56,4 +57,42 @@ void main() {
       expect(label, '11 Syawal 1447 H');
     });
   });
+
+  group('ScheduleCacheStatus', () {
+    test('derives cached date range and days left from stored schedules', () {
+      final status = ScheduleCacheStatus.fromSchedules(
+        [
+          DailyPrayerSchedule(
+            date: '2026-03-01',
+            imsak: '04:20',
+            subuh: '04:30',
+            terbit: '05:45',
+            dhuha: '06:10',
+            dzuhur: '11:55',
+            ashar: '15:10',
+            maghrib: '17:58',
+            isya: '19:05',
+          ),
+          DailyPrayerSchedule(
+            date: '2026-04-30',
+            imsak: '04:19',
+            subuh: '04:29',
+            terbit: '05:44',
+            dhuha: '06:09',
+            dzuhur: '11:54',
+            ashar: '15:09',
+            maghrib: '17:57',
+            isya: '19:04',
+          ),
+        ],
+        DateTime(2026, 3, 30),
+      );
+
+      expect(status.hasData, isTrue);
+      expect(status.startDate, DateTime(2026, 3, 1));
+      expect(status.endDate, DateTime(2026, 4, 30));
+      expect(status.cachedDays, 2);
+      expect(status.daysUntilRefresh, 31);
+    });
+  });
 }