Polish: npm test runs every test file, two silent failures now log, Loading placeholders shimmer

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

public/music.js

@@ -38,7 +38,7 @@ const mapTrack = (t, mc) => {
 
 async function viewMusic(args) {
   const v = $('#view');
-  v.innerHTML = '<div class="wrap"><h1>Music</h1><p class="empty">Loading…</p></div>';
+  v.innerHTML = '<div class="wrap"><h1>Music</h1><p class="empty loading" role="status">Loading…</p></div>';
   try {
     const st = await jfetch('/api/plex/status');
     if (!location.hash.startsWith('#/music')) return;