feat: SW update banner — notify instead of force-reload

- SW activate now posts SW_UPDATED message to all clients instead of
  calling client.navigate() (which was disruptive and unreliable)
- injectPWA() calls reg.update() on every app open to eagerly check
  for a new SW rather than waiting for the 24h browser interval
- showUpdateBanner() renders a persistent accent-bordered toast with
  version tag, a "Neu laden" button and a dismiss X
- Banner sits above player bar, repositions on mobile above bottom-nav

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.js

@@ -1329,9 +1329,38 @@ async function loadArtists(){
 
 // ─── PWA ───
 function injectPWA(){
-  if ('serviceWorker' in navigator) {
-    navigator.serviceWorker.register('sw.js').catch(() => {});
-  }
+  if (!('serviceWorker' in navigator)) return;
+  navigator.serviceWorker.register('sw.js').then(reg => {
+    // Force-check for SW update every time the app opens
+    reg.update().catch(() => {});
+    // New SW found while page is open (e.g. user left tab open overnight)
+    reg.addEventListener('updatefound', () => {
+      const sw = reg.installing;
+      if (!sw) return;
+      sw.addEventListener('statechange', () => {
+        // 'installed' + existing controller = update ready but waiting for skipWaiting
+        // With skipWaiting() this fires briefly; the SW_UPDATED message handles the banner
+      });
+    });
+  }).catch(() => {});
+
+  // SW posts SW_UPDATED after it activates and claims this client
+  navigator.serviceWorker.addEventListener('message', e => {
+    if (e.data?.type === 'SW_UPDATED') showUpdateBanner(e.data.version);
+  });
+}
+
+function showUpdateBanner(version) {
+  if (document.getElementById('update-banner')) return;
+  const b = document.createElement('div');
+  b.id = 'update-banner';
+  b.className = 'update-banner';
+  b.innerHTML = `
+    <span class="update-banner-text">✦ Update verfügbar${version ? ' <span style="opacity:.55;font-size:10px">('+version+')</span>' : ''}</span>
+    <button class="update-banner-btn" onclick="window.location.reload()">Neu laden</button>
+    <button class="update-banner-close" onclick="document.getElementById('update-banner').remove()">✕</button>
+  `;
+  document.body.appendChild(b);
 }
 
 

styles.css

@@ -704,6 +704,34 @@ nav{flex:1;overflow-y:auto;padding:4px 10px}
 .mobile-overlay{display:none;position:fixed;inset:0;background:rgba(0,0,0,.6);z-index:140}
 .mobile-overlay.active{display:block}
 
+/* ── UPDATE BANNER ── */
+.update-banner{
+  position:fixed;bottom:calc(var(--player-h) + 20px);left:50%;
+  transform:translateX(-50%);
+  display:flex;align-items:center;gap:10px;
+  background:var(--surface);border:1px solid var(--accent);
+  border-radius:12px;padding:10px 14px;
+  box-shadow:0 8px 32px rgba(0,0,0,.55),0 0 0 1px rgba(232,160,32,.15);
+  z-index:202;white-space:nowrap;
+  animation:toastIn .3s ease;
+}
+.update-banner-text{font-size:13px;font-weight:600;color:var(--text)}
+.update-banner-btn{
+  background:var(--accent);color:#000;border:none;
+  padding:6px 14px;border-radius:7px;
+  font-size:12px;font-weight:700;cursor:pointer;font-family:var(--font);
+  transition:opacity .15s;
+}
+.update-banner-btn:hover{opacity:.85}
+.update-banner-close{
+  background:none;border:none;color:var(--text3);
+  cursor:pointer;font-size:15px;padding:0 2px;line-height:1;
+}
+.update-banner-close:hover{color:var(--text)}
+@media(max-width:768px){
+  .update-banner{bottom:calc(var(--player-h) + 80px + 12px)}
+}
+
 /* ── SEARCH page ── */
 .search-section{margin-bottom:24px}
 .search-section-title{font-size:11px;font-weight:700;color:var(--text2);text-transform:uppercase;letter-spacing:.5px;margin-bottom:8px}

sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'ns-v27';
+const CACHE = 'ns-v28';
 const PRECACHE = ['/', 'index.html', 'styles.css', 'app.js', 'manifest.json', 'icon.svg'];
 const SKIP_PATHS = ['/rest/stream', '/rest/download', '/config.js'];
 
@@ -12,8 +12,8 @@ self.addEventListener('activate', e => {
     caches.keys()
       .then(keys => Promise.all(keys.filter(k => k !== CACHE).map(k => caches.delete(k))))
       .then(() => self.clients.claim())
-      .then(() => self.clients.matchAll({type: 'window', includeUncontrolled: true}))
-      .then(clients => clients.forEach(c => c.navigate(c.url)))
+      .then(() => self.clients.matchAll({ type: 'window', includeUncontrolled: true }))
+      .then(clients => clients.forEach(c => c.postMessage({ type: 'SW_UPDATED', version: CACHE })))
   );
 });