feat(album): plumb featured artists and parental warning

Add Album.parental_warning and Album.artists (with the new AlbumArtist
struct) to qbz-models so the /album/get response surfaces both fields.
Mirror them in the QobuzAlbum / AlbumDetail TypeScript types and
populate featuredArtists (filtered to non-main contributors) and
parentalWarning in convertQobuzAlbum. Wire onFeaturedArtistClick from
the route so featured artist names route to their discography.

cc

src/routes/+page.svelte

@@ -5922,6 +5922,7 @@
           isPlaybackActive={isPlaying}
           onBack={navGoBack}
           onArtistClick={() => selectedAlbum?.artistId && handleArtistClick(selectedAlbum.artistId)}
+          onFeaturedArtistClick={(artistId) => handleArtistClick(artistId)}
           onLabelClick={handleLabelClick}
           onAwardClick={handleAwardClick}
           onTrackPlay={handleAlbumTrackPlay}