feat: the Wanted view becomes Collection, shaped like Lidarr: an artist catalogue first, the state sections down a left rail (M502 #5577)

The section opens on a catalogue of every artist on the list, A–Z with a
letter rail, each card showing how many of their albums are held. An artist
opens on their page: every album of theirs, held or not, with its status,
search, releases and tracks. Wanted, Missing files, Activity, Following and
Blocked sit down a left rail as the sections that show state; Held is gone,
the catalogue shows it. The section moves from /wanted to /collection.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/lib/api/queries.ts

@@ -41,7 +41,9 @@ export const qk = {
     ['adminRequests', { status: status ?? 'all' }] as const,
   // Wanted list (M502 #5520). Wants sit under ['adminWants'] so one prefix
   // invalidation refreshes every tab and its counts.
-  adminWants:            (state: string, q: string = '') => ['adminWants', { state, q }] as const,
+  adminWants:            (state: string, q: string = '', artist: string = '') =>
+    ['adminWants', { state, q, artist }] as const,
+  wantArtists:           (q: string = '') => ['adminWants', 'artists', { q }] as const,
   wantTracks:            (id: string) => ['wantTracks', id] as const,
   adminFollows:          () => ['adminFollows'] as const,
   adminFollow:           (artistMbid: string) => ['adminFollow', artistMbid] as const,