feat: Audio-Eingang über WebSocket (/ws/voice) - Sprach-zu-Sprach (#4 Ausbau)

- /ws/voice: binaere Audio-Frames puffern, {"type":"end"} -> STT-Transkription
  -> transcript-Event -> bestehende Antwort-Pipeline (ack/token/audio/semantic/done)
- ws.py refaktoriert: gemeinsame _resolve + _run_turn fuer /ws/chat und /ws/voice
- stream/audio_stream auch fuer Sprach-Turns nutzbar; mehrere Utterances pro Verbindung
- Tests: 47 gruen (+2: Transkript->Antwort, leerer Puffer)
- Doku aktualisiert (README, BEDIENUNGSANLEITUNG, Architektur)

Hinweis: STT pro Aeusserung (gepuffert); partielle Live-Transkripte (Streaming-STT
mit VAD) bleiben naechster Increment.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_ws.py

@@ -66,3 +66,51 @@ def test_ws_requires_token_when_auth_enabled(monkeypatch):
     with pytest.raises(WebSocketDisconnect):
         with client.websocket_connect("/ws/chat"):
             pass
+
+
+def _install_voice_stubs(monkeypatch):
+    class StubSTT:
+        async def transcribe(self, audio_bytes, fmt, language=None):
+            return f"erkannt({len(audio_bytes)})"
+
+    class StubLLM:
+        async def complete(self, text, history=None, session_id=None):
+            return f"Antwort zu {text}"
+
+    class StubTTS:
+        async def synthesize(self, text, voice=None, audio_format="pcm"):
+            return b"VOICEAUD"
+
+    monkeypatch.setitem(deps.STT_REGISTRY, "ss", lambda s: StubSTT())
+    monkeypatch.setitem(deps.LLM_REGISTRY, "ll", lambda s: StubLLM())
+    monkeypatch.setitem(deps.TTS_REGISTRY, "tt", lambda s: StubTTS())
+    return {
+        "stt_provider": "ss",
+        "llm_provider": "ll",
+        "tts_provider": "tt",
+        "output_endpoint": "loopback",
+    }
+
+
+def test_ws_voice_transcribes_and_answers(monkeypatch):
+    opts = _install_voice_stubs(monkeypatch)
+    with client.websocket_connect("/ws/voice?session_id=v1") as ws:
+        ws.send_bytes(b"PCMDATA")          # 7 Bytes
+        ws.send_bytes(b"MORE")             # 4 Bytes -> insgesamt 11
+        ws.send_json({"type": "end", **opts})
+
+        transcript = ws.receive_json()
+        assert transcript["type"] == "transcript" and transcript["text"] == "erkannt(11)"
+        assert ws.receive_json()["type"] == "ack"
+        semantic = ws.receive_json()
+        assert semantic["type"] == "semantic" and semantic["text"] == "Antwort zu erkannt(11)"
+        assert ws.receive_bytes() == b"VOICEAUD"
+        assert ws.receive_json()["type"] == "done"
+
+
+def test_ws_voice_empty_buffer_errors(monkeypatch):
+    opts = _install_voice_stubs(monkeypatch)
+    with client.websocket_connect("/ws/voice") as ws:
+        ws.send_json({"type": "end", **opts})  # kein Audio gesendet
+        err = ws.receive_json()
+        assert err["type"] == "error" and "no audio" in err["detail"]