fix: mute sends silence frames instead of dropping uplink

ws/s2s-ws-client.js

@@ -578,8 +578,13 @@ export class S2sWsRealtimeClient extends EventTarget {
   _onMicChunk(pcm16Buffer) {
     if (!this._ws || this._ws.readyState !== WebSocket.OPEN) return;
     if (!this._sessionConfigured) return; // Server rejects audio before session.update.
-    if (this._muted) return;
-    const b64 = base64FromArrayBuffer(pcm16Buffer);
+    // While muted, keep the uplink flowing as pure silence instead of dropping
+    // frames. Privacy is preserved (no real mic audio leaves), while the
+    // server's audio clock keeps advancing so VAD sees trailing silence,
+    // soft-ends, and commits the pending turn. Mute thus acts as end-of-turn
+    // without stalling / disconnecting the session.
+    const buffer = this._muted ? new ArrayBuffer(pcm16Buffer.byteLength) : pcm16Buffer;
+    const b64 = base64FromArrayBuffer(buffer);
     this._send({ type: "input_audio_buffer.append", audio: b64 });
   }