feat: fans on local Navidrome artists (android) + harmonize web fan layout

- Android local artist page (ArtistDetailScreen/ArtistViewModel) now resolves the Deezer
  artist (fan-sorted, so same-name collisions pick the popular one) and shows "<n> Fans"
  under the name — parity with the web local artist page.
- Also migrated ArtistViewModel's preview to the app-level PreviewController: the local
  artist page had its OWN uncontrollable MediaPlayer preview, which had the same
  "keeps playing after navigating away" bug. Now every preview uses the global bar.
- Web: the artist-hero fan line was laid out in a row next to the name (flex without
  column direction) and used an odd tinted color — now stacked cleanly under the name in
  a muted white. SW ns-v54.
- CHANGELOG: documented the above + added a Known Bug (Android synced-lyrics auto-scroll
  still doesn't follow playback).

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

public/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'ns-v53';
+const CACHE = 'ns-v54';
 const PRECACHE = ['/', 'index.html', 'manifest.json', 'icon.svg'];
 const SKIP_PATHS = ['/rest/stream', '/rest/download', '/config.js'];
 // Auth token params stripped from cache keys so artwork survives across sessions/token refreshes.