fix(artist pin): apply pins in search + fix similar artists (web + android)

Two gaps the pin left, on both platforms:

1. Search still showed the wrong same-name artist's photo. The library search
   now prefers the pin's Deezer picture for a pinned artist (web: search.js
   artist cards; android: LibrarySearchContent via SearchViewModel overrides).

2. Similar Artists were "weird" — they come from Last.fm keyed to the (merged/
   wrong) Navidrome artist. When pinned, use Deezer "related" of the pinned
   artist instead (new deezerRelatedArtists / ItunesClient.lookupRelatedArtists).

Also: web Similar Artists now render with profile pictures (avatar chips), like
the Android app, instead of plain text chips.

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

src/api.js

@@ -412,6 +412,15 @@ export async function deezerLookupArtistSongs(artistId, limit=15) {
   } catch { return []; }
 }
 
+// Related Deezer artists (real pictures + fan counts). Used for the "Ähnliche Künstler" row when a
+// pin is active — Last.fm's similar list is keyed to the (possibly merged/wrong) Navidrome artist.
+export async function deezerRelatedArtists(artistId, limit=12) {
+  try {
+    const r = await fetch(`${_deezerBase()}/artist/${artistId}/related?limit=${limit}`);
+    return ((await r.json()).data || []).map(_dzArtist);
+  } catch { return []; }
+}
+
 // Deezer's /artist/{id}/albums list OMITS the artist object, so _dzAlbum yields artistName:''.
 // We already know whose page this is → backfill artistName so downstream download/detail cards
 // don't fall back to the literal "Unknown Artist" (which poisoned the yt-dlp search).