The previous implementation called LookupArtist (rate-limited MB API)
before fetching url-rels, wasting a rate limiter slot. The fetchURL
for rels also bypassed the MB rate limiter, risking 503 rejections.
Rewrite: fetch MB url-rels once (direct HTTP, cached 30 days), parse
both image and wikidata relations from the same response, resolve
Wikimedia thumb URL. No dependency on MusicBrainzClient — just the
Cache for storage and a plain http.Client.
Also cleared 34 stale cached empty results from previous failed
resolution attempts that were blocking image lookup.
Add ArtistImageProvider that resolves artist MBIDs to photo URLs:
1. MB url-rels 'image' type → extract Commons filename → thumb URL
2. MB url-rels 'wikidata' type → Wikidata P18 property → thumb URL
3. No image → falls back to initial-letter avatar
Wikimedia Commons thumb URLs constructed via MD5 hash bucketing
(standard Commons URL scheme). Results cached in explore_cache
with 30-day TTL — subsequent lookups are instant.
Frontend: search results and artist detail page show artist photos
in the circular avatar when available. Images load async and
replace the initial-letter fallback on arrival. Artist detail page
fires the image fetch alongside the other 4 parallel data loads.
Architecture supports adding more sources (fanart.tv, etc.) by
extending the resolve() method's source chain.
yonlu