Fix release notification resource and add multiple advance reminders

mobile/test/widgets/settings_test.dart

@@ -19,6 +19,43 @@ import 'package:hepan_everyday/domain/semester.dart';
 
 void main() {
   setUpAll(tzdata.initializeTimeZones);
+  testWidgets(
+    'reminder times can be selected together and last choice stays selected',
+    (tester) async {
+      final controller = uiController();
+      await controller.initialize();
+      await tester.pumpWidget(
+        MaterialApp(home: SettingsPage(controller: controller)),
+      );
+      await tester.pumpAndSettle();
+      await tester.scrollUntilVisible(
+        find.text('5 分钟'),
+        250,
+        scrollable: find.byType(Scrollable).first,
+      );
+      await tester.ensureVisible(find.text('5 分钟'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('5 分钟'));
+      await tester.pumpAndSettle();
+      expect(
+        (controller.snapshot.toJson()['settings'] as Map)['reminderOffsets'],
+        [5, 15],
+      );
+      await tester.tap(find.text('15 分钟'));
+      await tester.pumpAndSettle();
+      expect(
+        (controller.snapshot.toJson()['settings'] as Map)['reminderOffsets'],
+        [5],
+      );
+      await tester.tap(find.text('5 分钟'));
+      await tester.pumpAndSettle();
+      expect(
+        (controller.snapshot.toJson()['settings'] as Map)['reminderOffsets'],
+        [5],
+      );
+      controller.dispose();
+    },
+  );
   testWidgets(
     'partial initial calendar sync exposes working cleanup action while switch is off',
     (tester) async {