Fix external data pruning on item deletion

MediaBrowser.Controller/IO/IExternalDataManager.cs

@@ -16,4 +16,11 @@ public interface IExternalDataManager
     /// <param name="cancellationToken">The cancellation token.</param>
     /// <returns>Task.</returns>
     Task DeleteExternalItemDataAsync(BaseItem item, CancellationToken cancellationToken);
+
+    /// <summary>
+    /// Deletes only the filesystem-side external item data (attachments, subtitles, trickplay, chapter images).
+    /// Use this when DB-side cleanup is already handled by another code path (e.g. <c>IItemPersistenceService.DeleteItem</c>).
+    /// </summary>
+    /// <param name="item">The item.</param>
+    void DeleteExternalItemFiles(BaseItem item);
 }