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/api/admin_wanted_test.go

@@ -24,6 +24,7 @@ func doWantedReq(t *testing.T, h *handlers, path string, user dbq.User) *httptes
 	r.Route("/api/admin", func(admin chi.Router) {
 		admin.Use(auth.RequireAdmin())
 		admin.Get("/wanted", h.handleListWants)
+		admin.Get("/wanted/artists", h.handleListWantArtists)
 		admin.Get("/wanted/{id}/tracks", h.handleWantTracks)
 	})
 	w := httptest.NewRecorder()
@@ -98,6 +99,75 @@ func TestListWants_ArtistsAToZThenTheirAlbumsByDate(t *testing.T) {
 	}
 }
 
+// The Collection's catalogue (#5572): every artist on the list A–Z, each
+// with how many of their albums are held; an artist's page lists every album
+// of theirs, held or not, under that artist.
+func TestListWantArtists_CatalogueAndAnArtistsPage(t *testing.T) {
+	h, _ := testHandlersWithClientFn(t)
+	admin := seedUser(t, h.pool, "admin", "pw", true)
+	ctx := context.Background()
+	q := dbq.New(h.pool)
+	beatles := "a0000000-0000-4000-8000-000000000002"
+	camel := "a0000000-0000-4000-8000-000000000001"
+	if _, err := q.UpsertArtist(ctx, dbq.UpsertArtistParams{Name: "The Beatles", SortName: "Beatles, The", Mbid: &beatles}); err != nil {
+		t.Fatal(err)
+	}
+	seedWant(t, h, "g0000000-0000-4000-8000-000000000002", beatles, "The Beatles", "Abbey Road", "1969")
+	held := seedWant(t, h, "g0000000-0000-4000-8000-000000000003", beatles, "The Beatles", "Please Please Me", "1963")
+	if _, err := h.pool.Exec(ctx, `UPDATE wants SET fulfilled_at = now() WHERE id = $1`, held.ID); err != nil {
+		t.Fatal(err)
+	}
+	seedWant(t, h, "g0000000-0000-4000-8000-000000000004", camel, "Camel", "Moonmadness", "1976")
+	if _, err := h.pool.Exec(ctx, `INSERT INTO follows (artist_mbid, artist_name, profile_id)
+		SELECT $1, 'Camel', id FROM release_type_profiles WHERE is_default`, camel); err != nil {
+		t.Fatal(err)
+	}
+
+	w := doWantedReq(t, h, "/api/admin/wanted/artists", admin)
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d; body = %s", w.Code, w.Body.String())
+	}
+	var page wantArtistsPage
+	if err := json.Unmarshal(w.Body.Bytes(), &page); err != nil {
+		t.Fatal(err)
+	}
+	if len(page.Items) != 2 || page.Total != 2 || page.Counts.Artists != 2 {
+		t.Fatalf("catalogue = %+v, total %d, artists %d", page.Items, page.Total, page.Counts.Artists)
+	}
+	b, c := page.Items[0], page.Items[1]
+	if b.ArtistName != "The Beatles" || b.SortName != "Beatles, The" || b.Albums != 2 || b.Held != 1 || b.Wanted != 1 ||
+		b.ArtistID == "" || b.Following || b.ImageURL == "" {
+		t.Errorf("Beatles = %+v", b)
+	}
+	if c.ArtistName != "Camel" || c.Albums != 1 || c.Held != 0 || !c.Following || c.ArtistID != "" {
+		t.Errorf("Camel = %+v", c)
+	}
+
+	// q finds an artist by an album's title.
+	w = doWantedReq(t, h, "/api/admin/wanted/artists?q=moon", admin)
+	page = wantArtistsPage{}
+	if err := json.Unmarshal(w.Body.Bytes(), &page); err != nil {
+		t.Fatal(err)
+	}
+	if len(page.Items) != 1 || page.Items[0].ArtistName != "Camel" {
+		t.Errorf("q=moon: %+v", page.Items)
+	}
+
+	// The Beatles' page: both albums, held or not, headed by the artist.
+	w = doWantedReq(t, h, "/api/admin/wanted?state=all&artist="+beatles, admin)
+	var albums wantsPage
+	if err := json.Unmarshal(w.Body.Bytes(), &albums); err != nil {
+		t.Fatal(err)
+	}
+	if len(albums.Items) != 2 || albums.Items[0].Title != "Please Please Me" || albums.Items[0].HeldAt == nil ||
+		albums.Artist == nil || albums.Artist.Held != 1 {
+		t.Errorf("artist page = %+v, head %+v", albums.Items, albums.Artist)
+	}
+	if w := doWantedReq(t, h, "/api/admin/wanted?state=all&artist=nobody", admin); w.Code != http.StatusNotFound {
+		t.Errorf("an artist with nothing on the list: status %d, want 404", w.Code)
+	}
+}
+
 // fakeEditions is a MusicBrainz holding one group with two editions, the
 // shorter official one the standard, or 503 when down is set.
 func fakeEditions(t *testing.T, group string, down bool) *httptest.Server {