Added some animations, fixed crash when reopening folder

Photos/ViewModels/MainWindowViewModel.cs

@@ -35,7 +35,8 @@ public partial class MainWindowViewModel : ViewModelBase
         var folder = await _folderPickerService.PickFolderAsync();
         if (folder is null) return;
 
-        foreach(var p in Photos) p.Dispose();
+        // foreach(var p in Photos) p.Dispose();
+        Photos.Clear();
 
         LibraryPath = folder;
         await AddPhotosAsync(folder);