fix: Android lock screen notification + radio mode + SW auto-update reliability

- Set mediaSession.playbackState='playing'/'paused' so Android keeps the
  notification alive when the screen sleeps
- Provide 96x96/300x300/512x512 artwork sizes for Android notification views
- playQueue() now calls fillRadioQueue() immediately when radio mode is on,
  so the infinite queue works without toggling radio off/on
- SW: add GET_VERSION/VERSION message handler for version-query fallback
- SW registration: updateViaCache:'none' prevents browser HTTP-caching sw.js
- Bump cache to ns-v30

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

sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'ns-v29';
+const CACHE = 'ns-v30';
 const PRECACHE = ['/', 'index.html', 'styles.css', 'app.js', 'manifest.json', 'icon.svg'];
 const SKIP_PATHS = ['/rest/stream', '/rest/download', '/config.js'];
 
@@ -17,6 +17,12 @@ self.addEventListener('activate', e => {
   );
 });
 
+self.addEventListener('message', e => {
+  if (e.data?.type === 'GET_VERSION') {
+    e.source.postMessage({ type: 'VERSION', version: CACHE });
+  }
+});
+
 self.addEventListener('fetch', e => {
   if (!e.request.url.startsWith(self.location.origin)) return;
   if (SKIP_PATHS.some(p => e.request.url.includes(p))) return;