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>

internal/db/queries/wanted.sql

@@ -177,7 +177,7 @@ DELETE FROM wants WHERE id = $1;
 
 -- name: ListWants :many
 -- The Wanted page: open wants (all but missing ones, or only missing ones),
--- or the held ones. Ordered like the library (#5572): artists A–Z by the
+-- the held ones, or all of them; artist_mbid narrows to one artist's page. Ordered like the library (#5572): artists A–Z by the
 -- library's sort name when it holds the artist, each artist's albums by
 -- release date, so the page groups them as they arrive. q narrows to an
 -- artist or album title; total counts every match, past the page.
@@ -207,10 +207,12 @@ SELECT w.id, w.release_group_mbid, w.artist_mbid, w.artist_name, w.title, w.reas
   LEFT JOIN grabs gr ON gr.id = (SELECT x.id FROM grabs x WHERE x.want_id = w.id
                                    ORDER BY x.ended_at IS NULL DESC, x.grabbed_at DESC LIMIT 1)
  WHERE CASE sqlc.arg(state)::text
+         WHEN 'all'     THEN true
          WHEN 'held'    THEN w.fulfilled_at IS NOT NULL
          WHEN 'missing' THEN w.fulfilled_at IS NULL AND w.reason = 'missing'
          ELSE                w.fulfilled_at IS NULL AND w.reason <> 'missing'
        END
+   AND (sqlc.arg(artist_mbid)::text = '' OR w.artist_mbid = sqlc.arg(artist_mbid)::text)
    AND (sqlc.arg(q)::text = ''
         OR strpos(lower(w.artist_name), lower(sqlc.arg(q)::text)) > 0
         OR strpos(lower(w.title), lower(sqlc.arg(q)::text)) > 0)
@@ -219,6 +221,39 @@ SELECT w.id, w.release_group_mbid, w.artist_mbid, w.artist_name, w.title, w.reas
           lower(w.title), w.id
  LIMIT sqlc.arg(max_rows) OFFSET sqlc.arg(skip);
 
+-- name: ListWantArtists :many
+-- The Wanted view's main page (#5572): every artist on the list, A–Z like
+-- the library, with how many of their albums are held of how many are on
+-- the list. q matches the artist's name or any of their albums' titles;
+-- artist_mbid narrows to one artist, for their page's header.
+WITH a AS (
+    SELECT w.artist_mbid,
+           (array_agg(w.artist_name ORDER BY w.wanted_at DESC))[1]                 AS artist_name,
+           COUNT(*) FILTER (WHERE w.fulfilled_at IS NOT NULL)::int                AS held,
+           COUNT(*) FILTER (WHERE w.fulfilled_at IS NULL AND w.reason <> 'missing')::int AS wanted,
+           COUNT(*) FILTER (WHERE w.fulfilled_at IS NULL AND w.reason = 'missing')::int  AS missing,
+           COUNT(*)::int                                                          AS albums,
+           bool_or(sqlc.arg(q)::text <> '' AND strpos(lower(w.title), lower(sqlc.arg(q)::text)) > 0) AS title_match
+      FROM wants w
+     WHERE sqlc.arg(artist_mbid)::text = '' OR w.artist_mbid = sqlc.arg(artist_mbid)::text
+     GROUP BY w.artist_mbid
+)
+SELECT a.artist_mbid, a.artist_name::text AS artist_name, a.held, a.wanted, a.missing, a.albums,
+       COALESCE(NULLIF(la.sort_name, ''), a.artist_name)::text AS sort_name,
+       la.id AS library_artist_id,
+       (f.artist_mbid IS NOT NULL)::bool AS following,
+       (SELECT COUNT(*) FROM grabs g JOIN wants x ON x.id = g.want_id
+         WHERE x.artist_mbid = a.artist_mbid AND g.ended_at IS NULL)::int AS downloading,
+       COUNT(*) OVER () AS total
+  FROM a
+  LEFT JOIN LATERAL (SELECT ar.id, ar.sort_name FROM artists ar WHERE ar.mbid = a.artist_mbid LIMIT 1) la ON true
+  LEFT JOIN follows f ON f.artist_mbid = a.artist_mbid
+ WHERE sqlc.arg(q)::text = ''
+    OR strpos(lower(a.artist_name), lower(sqlc.arg(q)::text)) > 0
+    OR a.title_match
+ ORDER BY lower(COALESCE(NULLIF(la.sort_name, ''), a.artist_name)), a.artist_mbid
+ LIMIT sqlc.arg(max_rows) OFFSET sqlc.arg(skip);
+
 -- name: GetWantAlbum :one
 -- What the Wanted view's track list needs of a want (#5572).
 SELECT id, release_group_mbid, album_id FROM wants WHERE id = $1;
@@ -235,6 +270,7 @@ SELECT title, disc_number, track_number, duration_ms, (missing_since IS NOT NULL
 SELECT COUNT(*) FILTER (WHERE fulfilled_at IS NULL AND reason <> 'missing')::bigint AS wanted,
        COUNT(*) FILTER (WHERE fulfilled_at IS NULL AND reason = 'missing')::bigint  AS missing,
        COUNT(*) FILTER (WHERE fulfilled_at IS NOT NULL)::bigint                     AS held,
+       COUNT(DISTINCT artist_mbid)::bigint                                          AS artists,
        (SELECT COUNT(*) FROM follows)::bigint                                       AS following,
        -- The Wanted view's other tabs (#5522): downloads running, those
        -- waiting on a person, and releases set aside.