Two changes:
1. Artist image disk cache: ArtistImageProvider now fetches the
actual image bytes from Wikimedia Commons and caches them on
disk (~/.local/share/yellowjacket/artist-image-cache/{mbid}.jpg).
Returns base64 data URLs, same pattern as CoverArtProxy.
First lookup: resolve URL via MB/Wikidata + fetch image (~2s).
Subsequent: instant from disk cache.
404s cached as empty files to avoid re-fetching.
2. Top results artist photos: the Top Results section now shows
artist images from the artistImageCache, same as the Artists
section. Also shows englishName in the top card display name.