feat: a release catalogue from MusicBrainz; request search asks it directly (M502 #5519)

Minstrel keeps its own record of what artists have released, read from
MusicBrainz, so the wanted list, search and import no longer need Lidarr.

- internal/musicbrainz: searches (artists, release groups, recordings) and
  browses (an artist's release groups; a group's releases with track lists).
  One process-wide pacer at 1.1s, shared with tag enrichment, because
  MusicBrainz's limit is per address. A 503 throttle is retried.
- Migration 0080: mb_artists, mb_release_groups, mb_artist_release_groups
  (a collaboration belongs to each credited artist), mb_releases,
  mb_release_tracks.
- internal/catalogue: Discography and Releases serve the held copy and
  re-read it when older than 7 or 30 days. An unreachable MusicBrainz
  serves the stale copy, marked. An hourly pass re-reads due artists.
- Art for what isn't held comes through /api/catalogue/art from the
  enabled cover-art sources (Cover Art Archive by release group, then the
  name-based sources) and is kept on disk, so the browser never fetches a
  third-party host. A miss is a 404 and the card shows its icon.
- Request search moves from /api/lidarr/search to /api/catalogue/search,
  with the same response shape. Albums are release groups, and "in
  library" matches albums.release_group_mbid. A 10-minute cache absorbs
  search-as-you-type. Discover suggestions point at the art endpoint
  instead of looking up Lidarr.
- Android calls the new path and loads Discover art through ServerImage.
  Installed builds older than this one lose Discover search until they
  update (no compatibility path, rule 22).

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

web/src/lib/components/DiscoverResultCard.svelte

@@ -28,12 +28,21 @@
     state: DiscoverCardState;
     attribution?: string;
     onRequest?: () => void;
-    // Omit both to get a card with no snooze affordance — the Lidarr search
+    // Omit both to get a card with no snooze affordance — the catalogue search
     // results reuse this component and have nothing to park.
     onSnooze?: () => void;
     onUnsnooze?: () => void;
   } = $props();
 
+  // Art comes from Minstrel's catalogue endpoint, which answers 404 when no
+  // source has an image (M502 #5519): show the icon then, not a broken image.
+  // Reset when the card is reused for another result.
+  let imageFailed = $state(false);
+  $effect(() => {
+    void imageUrl;
+    imageFailed = false;
+  });
+
   const FallbackIcon = $derived(
     kind === 'artist' ? Disc3 : kind === 'album' ? Album : Music2
   );
@@ -50,12 +59,13 @@
   <div
     class="art flex aspect-square w-full items-center justify-center overflow-hidden rounded-md bg-surface-hover"
   >
-    {#if imageUrl}
+    {#if imageUrl && !imageFailed}
       <img
         src={imageUrl}
         alt=""
         loading="lazy"
         class="h-full w-full object-cover"
+        onerror={() => (imageFailed = true)}
       />
     {:else}
       <FallbackIcon size={32} strokeWidth={1} class="text-text-muted" />

web/src/lib/components/DiscoverResultCard.test.ts

@@ -168,4 +168,20 @@ describe('DiscoverResultCard', () => {
     expect(onUnsnooze).toHaveBeenCalledOnce();
     expect(onRequest).not.toHaveBeenCalled();
   });
+
+  test('an image that fails to load falls back to the icon', async () => {
+    const { container } = render(DiscoverResultCard, {
+      props: {
+        kind: 'artist',
+        title: 'Boards of Canada',
+        state: 'requestable',
+        imageUrl: '/api/catalogue/art/artist/x',
+      },
+    });
+    const img = container.querySelector('img');
+    expect(img).not.toBeNull();
+    await fireEvent.error(img!);
+    expect(container.querySelector('img')).toBeNull();
+    expect(container.querySelector('.art svg')).not.toBeNull();
+  });
 });