feat(web): cover art on Wanted + Discover album rows

Wanted API returns rgMbid/type/year; Wanted rows show a cover thumb and open
the album modal. Discover suggested-album rows get a cover thumb too. Completes
cover art across the app (artist detail, Library, modals, Wanted, Discover).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/app/api/wanted/route.ts

@@ -15,6 +15,9 @@ export async function GET() {
       currentQualityClass: r.currentQualityClass,
       lastSearchedAt: r.lastSearchedAt,
       watchedArtistId: r.watchedArtistId,
+      rgMbid: r.rgMbid,
+      primaryType: r.primaryType,
+      firstReleaseDate: r.firstReleaseDate,
     })),
   });
 }