feat: Implement offline library synchronization with IndexedDB

- Added `useOfflineLibrarySync` hook for managing offline library sync operations.
- Created `OfflineLibrarySync` component for UI integration.
- Developed `offlineLibraryDB` for IndexedDB interactions, including storing and retrieving albums, artists, songs, and playlists.
- Implemented sync operations for starred items, playlists, and scrobbling.
- Added auto-sync functionality when coming back online.
- Included metadata management for sync settings and statistics.
- Enhanced error handling and user feedback through toasts.

hooks/use-offline-audio-player.ts

@@ -46,6 +46,8 @@ export function useOfflineAudioPlayer() {
       if (offlineStatus) {
         track.isOffline = true;
         track.offlineUrl = `offline-song-${song.id}`;
+        // Prefer offline cached URL to avoid re-streaming even when online
+        track.url = track.offlineUrl;
       }
     }