fix: fallback auto grouping to day grouping (#20156)

fallback auto grouping to day grouping

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>

mobile/lib/domain/models/timeline.model.dart

@@ -3,6 +3,7 @@ import 'package:immich_mobile/domain/utils/event_stream.dart';
 enum GroupAssetsBy {
   day,
   month,
+  auto,
   none;
 }
 

mobile/lib/domain/services/timeline.service.dart

@@ -33,8 +33,12 @@ class TimelineFactory {
   })  : _timelineRepository = timelineRepository,
         _settingsService = settingsService;
 
-  GroupAssetsBy get groupBy =>
-      GroupAssetsBy.values[_settingsService.get(Setting.groupAssetsBy)];
+  GroupAssetsBy get groupBy {
+    final group =
+        GroupAssetsBy.values[_settingsService.get(Setting.groupAssetsBy)];
+    // We do not support auto grouping in the new timeline yet, fallback to day grouping
+    return group == GroupAssetsBy.auto ? GroupAssetsBy.day : group;
+  }
 
   TimelineService main(List<String> timelineUsers) =>
       TimelineService(_timelineRepository.main(timelineUsers, groupBy));