- Add database migration for `generated_playlist_covers` table to track playlist cover jobs
- Implement backend routes for generating, polling, and applying playlist cover art via ComfyUI
- Add `comfyui_node_image_seed` setting to allow configurable seeds for image generation
- Update UI to show "Generate Cover Art" link on playlist forms when image generation is enabled
- Add service worker update notification banner with refresh and dismiss options
- Enhance player with push notifications for now-playing updates
- Update service worker to handle notification clicks and improve caching strategy
