Complete LinkedChildren integration and batch DTO optimizations

This commit integrates remaining performance changes:

- Add batch user data fetching in DtoService to reduce N+1 queries
- Add GetNextUpEpisodesBatch in TVSeriesManager for efficient batch retrieval
- Update Video/Movie/BoxSet to use LibraryManager for alternate versions
- Transition LinkedChild to use ItemId instead of Path (obsolete Path/LibraryItemId)
- Update providers and controllers for LinkedChildren-based references
- Add NextUpEpisodeBatchResult for batched episode queries
- Integrate IDescendantQueryProvider in SqliteDatabaseProvider

MediaBrowser.Controller/Entities/CollectionFolder.cs

@@ -44,6 +44,11 @@ namespace MediaBrowser.Controller.Entities
             PhysicalFolderIds = Array.Empty<Guid>();
         }
 
+        /// <summary>
+        /// Event raised when library options are updated for any collection folder.
+        /// </summary>
+        public static event EventHandler<LibraryOptionsUpdatedEventArgs> LibraryOptionsUpdated;
+
         /// <summary>
         /// Gets the display preferences id.
         /// </summary>
@@ -168,6 +173,8 @@ namespace MediaBrowser.Controller.Entities
             }
 
             XmlSerializer.SerializeToFile(clone, GetLibraryOptionsPath(path));
+
+            LibraryOptionsUpdated?.Invoke(null, new LibraryOptionsUpdatedEventArgs(path, options));
         }
 
         public static void OnCollectionFolderChange()