Fix deleted playlists resurrecting from iCloud after app restart

Pending deletes were lost across app restarts because
recoverPersistedPendingChanges() never reconstructed CKRecord.ID
objects from persisted record names. Additionally, incoming iCloud
records for deleted playlists were blindly applied, and orphaned
playlist items in CloudKit would recreate placeholder playlists.

- Rebuild pendingDeletes array from UserDefaults on recovery
- Guard applyRemoteRecord against records pending local deletion
- Skip deferred items whose parent playlist is pending deletion
- Queue all playlist item deletions when deleting a playlist
- Clean up placeholder playlists for pending-delete playlists

Yattee/Data/DataManager+Playlists.swift

@@ -40,12 +40,17 @@ extension DataManager {
     /// Deletes a local playlist.
     func deletePlaylist(_ playlist: LocalPlaylist) {
         let playlistID = playlist.id
+        let itemIDs = playlist.sortedItems.map { $0.id }
+
         modelContext.delete(playlist)
         save()
-        
-        // Queue for CloudKit deletion
+
+        // Queue playlist and all its items for CloudKit deletion
         cloudKitSync?.queuePlaylistDelete(playlistID: playlistID)
-        
+        for itemID in itemIDs {
+            cloudKitSync?.queuePlaylistItemDelete(itemID: itemID)
+        }
+
         NotificationCenter.default.post(name: .playlistsDidChange, object: nil)
     }