PlaylistSyncService now accepts profile_id and applies per-profile
library selection before syncing. _apply_profile_library sets Plex
library name or Jellyfin user/library on the client based on the
profile's saved preferences. All existing _get_active_media_client
calls automatically pick up the active profile via instance state.
Admin and profiles without custom library settings: zero change.
Enhanced handling of artist data to support both string and object formats across the database, sync service, and web server. The sync process now preserves full album and artist objects for tracks, enabling wishlist additions with album cover art. The frontend and API were updated to use the full artist objects, and the UI now formats artist names correctly.
