feat(barge-in): Unterbrechen der KI-Antwort per Mikrofon-Button und Enter

Web-Interface (app.js):
- Mic-Button hat jetzt 3 Zustände: idle (grün 🎤) / Aufnahme (rot pulsierend) /
  KI antwortet (amber ⏹, klicken = Barge-in)
- Barge-in sendet {"type":"interrupt"} auf der aktiven WS-Verbindung (activeWs)
  und stoppt alle laufenden AudioBufferSourceNodes sofort (stopAudio)
- busy + Button-Reset erfolgen automatisch wenn die WS schliesst

Terminal (voice_loop.py):
- _stdin_watcher(): polling via select.select (nicht-blockierend, kein Thread-Leak)
  wartet auf Enter-Tastendruck waehrend Server antwortet
- _send_and_play() raced one_turn gegen _stdin_watcher mit asyncio.wait;
  bei Barge-in: interrupt-Frame an Server, Player.terminate(), feeder beenden
- Feedback: "↩ Unterbrochen — drücke [Enter] für neue Aufnahme …"

Server-Seite war bereits vollstaendig implementiert (ws.py, kein Handlungsbedarf).

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

app/web/app.js

@@ -16,6 +16,9 @@ function overrides() {
 }
 
 let busy = false;
+let activeWs = null;     // aktive WS-Verbindung (fuer Barge-in von aussen erreichbar)
+let activeSources = [];  // laufende AudioBufferSourceNodes (stoppbar per Barge-in)
+
 // Session-ID pro Nutzer (sonst "gehoert einem anderen Nutzer"-Konflikt). Wird aus
 // /api/me abgeleitet; bis dahin null -> ensureSession() wartet auf loadMe().
 let sessionId = null;
@@ -99,6 +102,32 @@ function addMessage(role, text) {
   return div;
 }
 
+// ---------- Barge-in-Hilfsfunktionen ----------
+function stopAudio() {
+  activeSources.forEach((s) => { try { s.stop(); } catch (e) {} });
+  activeSources = [];
+}
+
+function setMicIdle() {
+  micBtn.textContent = "🎤";
+  micBtn.title = "Mikrofon";
+  micBtn.classList.remove("bg-red-600", "animate-pulse", "bg-amber-500");
+  micBtn.classList.add("bg-emerald-600");
+}
+
+function setMicRecording() {
+  micBtn.classList.remove("bg-emerald-600", "bg-amber-500");
+  micBtn.classList.add("bg-red-600", "animate-pulse");
+  micBtn.title = "Aufnahme stoppen";
+}
+
+function setMicBusy() {
+  micBtn.textContent = "⏹";
+  micBtn.title = "KI unterbrechen (Barge-in)";
+  micBtn.classList.remove("bg-emerald-600", "bg-red-600", "animate-pulse");
+  micBtn.classList.add("bg-amber-500");
+}
+
 // ---------- Audio-Wiedergabe (PCM s16le) ----------
 let audioCtx = null;
 function playPcm(chunks, sampleRate) {
@@ -116,6 +145,8 @@ function playPcm(chunks, sampleRate) {
   const src = audioCtx.createBufferSource();
   src.buffer = buf;
   src.connect(audioCtx.destination);
+  activeSources.push(src);
+  src.onended = () => { activeSources = activeSources.filter((s) => s !== src); };
   src.start();
 }
 
@@ -129,6 +160,7 @@ function wsUrl(path) {
 function runTurn(path, onopen) {
   return new Promise((resolve) => {
     const ws = new WebSocket(wsUrl(path));
+    activeWs = ws;
     ws.binaryType = "arraybuffer";
     const pcm = [];
     let answerEl = null;
@@ -136,7 +168,7 @@ function runTurn(path, onopen) {
 
     ws.onopen = () => onopen(ws);
     ws.onerror = () => { statusEl.textContent = "Verbindungsfehler"; resolve(); };
-    ws.onclose = () => resolve();
+    ws.onclose = () => { activeWs = null; resolve(); };
 
     ws.onmessage = (event) => {
       if (typeof event.data !== "string") { pcm.push(event.data); return; }
@@ -179,6 +211,7 @@ function runTurn(path, onopen) {
 async function sendText(text) {
   if (busy || !text.trim()) return;
   busy = true;
+  setMicBusy();
   await ensureSession();
   addMessage("user", text);
   statusEl.textContent = "denkt …";
@@ -186,6 +219,7 @@ async function sendText(text) {
     ws.send(JSON.stringify({ text, stream: true, audio_stream: true, ...overrides() }));
   });
   busy = false;
+  setMicIdle();
 }
 
 formEl.addEventListener("submit", (e) => {
@@ -236,20 +270,19 @@ async function startRecording() {
     sendVoice(bytes, mime.includes("mp4") || mime.includes("mpeg") ? "mp4" : "webm");
   };
   mediaRecorder.start();
-  micBtn.classList.remove("bg-emerald-600");
-  micBtn.classList.add("bg-red-600", "animate-pulse");
+  setMicRecording();
   statusEl.textContent = "Aufnahme … (zum Stoppen erneut tippen)";
 }
 
 function stopRecording() {
   if (mediaRecorder && mediaRecorder.state !== "inactive") mediaRecorder.stop();
-  micBtn.classList.remove("bg-red-600", "animate-pulse");
-  micBtn.classList.add("bg-emerald-600");
+  setMicIdle();
 }
 
 async function sendVoice(bytes, fmt = "webm") {
   if (busy) return;
   busy = true;
+  setMicBusy();
   await ensureSession();
   statusEl.textContent = "verarbeite Sprache …";
   await runTurn("/ws/voice", (ws) => {
@@ -258,11 +291,21 @@ async function sendVoice(bytes, fmt = "webm") {
     ws.send(JSON.stringify({ type: "end" }));
   });
   busy = false;
+  setMicIdle();
 }
 
 micBtn.addEventListener("click", () => {
-  if (mediaRecorder && mediaRecorder.state === "recording") stopRecording();
-  else startRecording();
+  if (busy) {
+    // Barge-in: laufende KI-Antwort sofort unterbrechen
+    if (activeWs) activeWs.send(JSON.stringify({ type: "interrupt" }));
+    stopAudio();
+    statusEl.textContent = "Unterbrochen";
+    // busy + Button-Reset erfolgen sobald die WS schliesst (-> runTurn resolve -> sendVoice/sendText)
+  } else if (mediaRecorder && mediaRecorder.state === "recording") {
+    stopRecording();
+  } else {
+    startRecording();
+  }
 });
 
 $("#reload-users").addEventListener("click", loadUsers);