Music: Mixes, Favorites and Stats; smart and Family playlists; library radio; offline albums; more

- Mixes tab: daily mix, most played, forgotten favorites, moods, on this day, decades, genres, smart playlists (rules), library radio
- Favorites (hearts, kept by the hub) and Stats (plays, time, top artists/songs/albums, streak, recently played)
- Family playlists shared by everyone with Music; queue reorder; More like this; album/artist About notes
- Save albums offline; player takes colors from the cover; Share a lyric line as a picture; verse of the day on Featured
- musicdata.js keeps plays, favorites, smart rules and Family playlists, with tests

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

public/sw.js

@@ -1,5 +1,5 @@
 // App-shell cache only; Seafile/API traffic always goes to the network.
-const CACHE = 'hub-v56';
+const CACHE = 'hub-v57';
 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'];
 
@@ -46,6 +46,7 @@ self.addEventListener('fetch', e => {
   const u = new URL(e.request.url);
   if (e.request.method === 'POST' && u.origin === location.origin && u.pathname === '/share-target') return e.respondWith(takeShare(e.request));
   if (e.request.method === 'GET' && u.origin === location.origin && /^\/api\/podcast\/podcasts\/[^/]+\/file$/.test(u.pathname)) return e.respondWith(offlineAudio(e.request));
+  if (e.request.method === 'GET' && u.origin === location.origin && /^\/plex\/library\/parts\//.test(u.pathname)) return e.respondWith(offlineAudio(e.request)); // (albums saved on this device)
   if (e.request.method !== 'GET' || u.origin !== location.origin || u.pathname.startsWith('/sf/') || u.pathname.startsWith('/plex/') || u.pathname.startsWith('/api/')) return;
   e.respondWith(fetch(e.request).then(r => {
     if (r.ok) { const copy = r.clone(); caches.open(CACHE).then(c => c.put(e.request, copy)); }