feat(artists): sort control on the roster

Add a Sort dropdown to /artists next to the filter: Recently followed
(default, createdAt desc — the prior order), Name A–Z, Most in library,
Most monitored, Most releases. Client-side sort of the already-fetched
roster; the filter box and "In library, not followed" section are
unchanged. Exposes WatchedArtist.createdAt on /api/artists for the sort.

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

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

@@ -38,6 +38,7 @@ export async function GET(request: Request) {
         id: a.id,
         mbid: a.mbid,
         name: a.name,
+        createdAt: a.createdAt,
         autoMonitorFuture: a.autoMonitorFuture,
         showAllTypes: a.showAllTypes,
         releaseCount: visible.length,

web/src/app/artists/artists-client.tsx

@@ -10,6 +10,7 @@ type Artist = {
   id: string;
   mbid: string;
   name: string;
+  createdAt: string;
   autoMonitorFuture: boolean;
   releaseCount: number;
   monitoredCount: number;
@@ -17,11 +18,21 @@ type Artist = {
 };
 type Hit = { mbid: string; name: string; disambiguation: string };
 
+type SortKey = "followed" | "name" | "have" | "monitored" | "releases";
+const SORTS: { key: SortKey; label: string; cmp: (a: Artist, b: Artist) => number }[] = [
+  { key: "followed", label: "Recently followed", cmp: (a, b) => b.createdAt.localeCompare(a.createdAt) },
+  { key: "name", label: "Name A–Z", cmp: (a, b) => a.name.localeCompare(b.name) },
+  { key: "have", label: "Most in library", cmp: (a, b) => b.haveCount - a.haveCount || a.name.localeCompare(b.name) },
+  { key: "monitored", label: "Most monitored", cmp: (a, b) => b.monitoredCount - a.monitoredCount || a.name.localeCompare(b.name) },
+  { key: "releases", label: "Most releases", cmp: (a, b) => b.releaseCount - a.releaseCount || a.name.localeCompare(b.name) },
+];
+
 export function ArtistsClient() {
   const [artists, setArtists] = useState<Artist[]>([]);
   const [ownedNotFollowed, setOwnedNotFollowed] = useState<string[]>([]);
   const [justFollowed, setJustFollowed] = useState<Set<string>>(new Set());
   const [filter, setFilter] = useState("");
+  const [sort, setSort] = useState<SortKey>("followed");
   const [showAdd, setShowAdd] = useState(false);
   const [query, setQuery] = useState("");
   const [hits, setHits] = useState<Hit[]>([]);
@@ -113,8 +124,10 @@ export function ArtistsClient() {
   const followedMbids = new Set(artists.map((a) => a.mbid));
   const shown = useMemo(() => {
     const n = filter.trim().toLowerCase();
-    return n ? artists.filter((a) => a.name.toLowerCase().includes(n)) : artists;
-  }, [artists, filter]);
+    const filtered = n ? artists.filter((a) => a.name.toLowerCase().includes(n)) : artists;
+    const cmp = (SORTS.find((s) => s.key === sort) ?? SORTS[0]).cmp;
+    return [...filtered].sort(cmp);
+  }, [artists, filter, sort]);
   const ownedShown = useMemo(
     () => ownedNotFollowed.filter((name) => !justFollowed.has(name)),
     [ownedNotFollowed, justFollowed],
@@ -137,6 +150,14 @@ export function ArtistsClient() {
             onChange={(e) => setFilter(e.target.value)}
           />
         </label>
+        <label className="field">
+          <span>Sort</span>
+          <select aria-label="sort artists" value={sort} onChange={(e) => setSort(e.target.value as SortKey)}>
+            {SORTS.map((s) => (
+              <option key={s.key} value={s.key}>{s.label}</option>
+            ))}
+          </select>
+        </label>
       </div>
 
       <SectionHeader