- Theme: hex color regex + background shade enum validation - Tracklist: column ID recognition + duplicate detection - Favorites: icon style enum validation - Library: directory existence + scan concurrency mode validation - Config: load/save roundtrip, missing file handling, composed errors, defaults
- Add PinDefault bool to favorites.Config struct with TOML tag - Add GetPinDefaultPlaylist() and SetPinDefaultPlaylist() methods - Include PinDefault in emitFavoritesChanged event payload - Default to true (pinned) for new config installations