fix(library): show album cover art in the Albums grid

The album cards always fell back to the 💿 placeholder: the mapper dropped
the backend's `has_cover` and no album cover URL was ever built. Carry
`hasCover` through `RawAlbum`/`Album` and add `getAlbumCoverUrl` (GET
/albums/{id}/cover, token in the query like the track/stream URLs). The
Library Albums grid and the artist-detail discography now render real
covers, same source the album-detail page already used.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/api/endpoints/streaming.ts

@@ -32,3 +32,18 @@ export function getTrackCoverUrl(
   const base = getApiBaseUrl();
   return `${base}/tracks/${trackId}/cover?token=${encodeURIComponent(token)}`;
 }
+
+/**
+ * Cover image URL for an album, served by `GET /albums/{id}/cover`. Same
+ * `?token=` rationale as the track cover. Returns undefined when the album has
+ * no cover (so callers fall back to generated tile art).
+ */
+export function getAlbumCoverUrl(
+  albumId: string,
+  token: string,
+  hasCover: boolean,
+): string | undefined {
+  if (!hasCover) return undefined;
+  const base = getApiBaseUrl();
+  return `${base}/albums/${albumId}/cover?token=${encodeURIComponent(token)}`;
+}

src/api/mappers.ts

@@ -95,6 +95,7 @@ export interface RawAlbum {
   artist_name: string;
   year: number | null;
   track_count: number;
+  has_cover: boolean;
   created_at: string;
 }
 
@@ -171,7 +172,10 @@ export const toAlbum = (r: RawAlbum): Album => ({
   title: r.title,
   artistId: r.artist_id,
   artistName: r.artist_name,
+  // The album record carries no cover *URL*; `hasCover` says one exists, and the
+  // URL (which needs `?token=`) is built in components via `getAlbumCoverUrl`.
   artUrl: undefined,
+  hasCover: r.has_cover,
   year: r.year ?? undefined,
   trackCount: r.track_count,
   // AlbumOut has no aggregate duration; computed client-side from tracks when

src/api/types.ts

@@ -44,6 +44,8 @@ export interface Album {
   artistId: string;
   artistName: string;
   artUrl?: string;
+  /** Whether the album has cover art served by `GET /albums/{id}/cover`. */
+  hasCover: boolean;
   year?: number;
   trackCount: number;
   totalDurationMs: number;