Keep iPhone audio playing through background handoffs

frontend/index.html

@@ -662,6 +662,7 @@
     <script src="p2p-transfer.js"></script>
     <script src="async-guard.js"></script>
     <script src="sw-update.js"></script>
+    <script src="audio-continuity.js"></script>
     <script src="fullscreen-orientation.js"></script>
     <script src="settings-sections.js"></script>
     <script src="direct-protocol.js"></script>