feat: update user playlists schema and related functionality
- Added new entries to the journal for tracking purposes.
- Changed the import from tracks to playlists in user-playlists schema.
- Updated the playlistId reference in user-playlists to point to playlists instead of tracks.
- Modified the insert_album_track function to remove xata_createdat from the insert statement.
- Updated the insert_playlist_track function to remove added_by from the insert statement.
- Removed added_by field from the PlaylistTrack struct in xata.