migrated custom timetable events to Marianum-Connect and refactored push notification handling

lib/push/push_registration_store.dart

@@ -27,6 +27,11 @@ class PushRegistrationStore {
   // (AccountData writes `nextcloud_app_password` group-scoped).
   static const _usernameKey = 'nextcloud_username';
   static const _baseUrlKey = 'nextcloud_base_url';
+  // Mirror of the in-app notification toggle (`notificationSettings.enabled`),
+  // written group-scoped so the FCM background isolate (no bloc access) and the
+  // iOS NSE can gate rendering. The device stays *registered* when off so silent
+  // sync pushes keep flowing — only the visible alert is suppressed.
+  static const _notificationsEnabledKey = 'push_notifications_enabled';
 
   static const _perTypeKeys = [
     _deviceIdentifierKey,
@@ -82,6 +87,19 @@ class PushRegistrationStore {
     await _storage.write(key: _baseUrlKey, value: baseUrl);
   }
 
+  /// Mirrors the in-app notification toggle so the background isolate / iOS NSE
+  /// can read it without bloc access.
+  Future<void> setNotificationsEnabled(bool enabled) =>
+      _storage.write(
+        key: _notificationsEnabledKey,
+        value: enabled ? '1' : '0',
+      );
+
+  /// The mirrored notification toggle. Defaults to `true` when unset (fresh
+  /// install / pre-mirror build) so a missing mirror never silences pushes.
+  Future<bool> notificationsEnabled() async =>
+      await _storage.read(key: _notificationsEnabledKey) != '0';
+
   Future<String?> deviceIdentifier(PushRegistrationType type) =>
       _storage.read(key: keyFor(_deviceIdentifierKey, type));