feat: decompose frontend into native ES modules (zero bundlers, zero npm)

app/static/index.html

@@ -1075,7 +1075,7 @@
     <!-- Audio Element for native streaming -->
     <audio id="global-audio-player" preload="none"></audio>
 
-    <script src="/static/js/app.js?v=4.0"></script>
+    <script type="module" src="/static/js/app.js?v=5.0"></script>
 </body>
 </html>