Music on iPhone: keep 3-5 songs ready (size-capped), skip a song that will not load instead of sticking on Buffering, tidy the album buttons, lock-screen art in more sizes, and accept the lookups and song-cache settings on the server

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaC9HmtHMdRP8dAbN4wAKj

public/sw.js

@@ -1,5 +1,5 @@
 // App-shell cache only; Seafile/API traffic always goes to the network.
-const CACHE = 'hub-v137';
+const CACHE = 'hub-v138';
 const KEEP = /^hub-(offline|share|who|data-)/; // caches that outlive a new version
 const SHARE = 'hub-share'; // files shared into the app from other apps, held until the person picks a folder
 const SHELL = ['/icon.svg', '/manifest.webmanifest', '/icons/icon-192.png', '/icons/apple-touch-icon.png'];