fix(mobile): blank notifications page after enabling notifications (#29232)

the old notification toggles were removed in a cleanup, so once notifications were enabled the page had nothing left and went blank. show a "notifications enabled" status tile with a shortcut to the system notification settings instead.

i18n/en.json

@@ -1507,6 +1507,9 @@
   "notes": "Notes",
   "nothing_here_yet": "Nothing here yet",
   "notification_backup_reliability": "Enable notifications to improve background backup reliability",
+  "notification_enabled_list_tile_content": "Immich uses notifications for background backup. Manage them in your device settings.",
+  "notification_enabled_list_tile_open_button": "Open settings",
+  "notification_enabled_list_tile_title": "Notifications enabled",
   "notification_permission_dialog_content": "To enable notifications, go to Settings and select allow.",
   "notification_permission_list_tile_content": "Grant permission to enable notifications.",
   "notification_permission_list_tile_enable_button": "Enable Notifications",

mobile/lib/widgets/settings/notification_setting.dart

@@ -48,6 +48,14 @@ class NotificationSetting extends HookConsumerWidget {
                   showPermissionsDialog();
                 }
               }),
+        )
+      else
+        SettingsButtonListTile(
+          icon: Icons.notifications_active_outlined,
+          title: 'notification_enabled_list_tile_title'.tr(),
+          subtileText: 'notification_enabled_list_tile_content'.tr(),
+          buttonText: 'notification_enabled_list_tile_open_button'.tr(),
+          onButtonTap: () => openAppSettings(),
         ),
     ];