feat(tts): Chatterbox-Provider (hohe Qualitaet + Voice-Cloning) anbinden

Loest #7. Der chatterbox-Stub wird durch eine echte Anbindung an den lokalen
Chatterbox-HTTP-Dienst ersetzt (POST /speak -> /status pollen -> GET /audio, WAV).
no_playback=true -> der Dienst spielt nicht lokal ab, liefert nur Bytes. WAV->PCM
(24 kHz, Resampling bei Bedarf). Waehlbar via tts_provider=chatterbox; piper bleibt
der schnelle Default (chatterbox ist ~echtzeit-langsam, dafuer klonbare Stimme).

- config: CHATTERBOX_BASE_URL/_VOICE/_LANG/_SPEED/_TIMEOUT; Registry verdrahtet
- Tests: gemockter httpx (Synthese, WAV/Resample, Job-Fehler, Stimmenwahl)
- Doku: README, Architektur (#7), deploy/README (GPU-Pinning per UUID, no_playback)

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

tests/test_chatterbox_tts.py

@@ -0,0 +1,82 @@
+import io
+import wave
+
+import httpx
+import pytest
+
+import app.providers.tts.chatterbox as cb
+from app.providers.tts.chatterbox import ChatterboxTTSProvider
+
+
+def _wav(rate=24000, payload=b"\x01\x02" * 2400) -> bytes:
+    buf = io.BytesIO()
+    with wave.open(buf, "wb") as w:
+        w.setnchannels(1)
+        w.setsampwidth(2)
+        w.setframerate(rate)
+        w.writeframes(payload)
+    return buf.getvalue()
+
+
+def _install(monkeypatch, handler):
+    real = httpx.AsyncClient  # echte Klasse sichern (vor dem Patch)
+
+    def make_client(*args, **kwargs):
+        kwargs.pop("timeout", None)
+        return real(transport=httpx.MockTransport(handler))
+    monkeypatch.setattr(cb.httpx, "AsyncClient", make_client)
+
+
+def _ok_handler(status="done", wav_rate=24000):
+    def handler(request: httpx.Request) -> httpx.Response:
+        p = request.url.path
+        if request.method == "POST" and p == "/speak":
+            return httpx.Response(200, json={"job_id": "j1", "status": "pending"})
+        if p == "/status":
+            return httpx.Response(200, json={"recent_jobs": [{"id": "j1", "status": status,
+                                                              "error": "boom" if status == "error" else None}]})
+        if p == "/audio/j1":
+            return httpx.Response(200, content=_wav(wav_rate), headers={"content-type": "audio/wav"})
+        return httpx.Response(404)
+    return handler
+
+
+def test_synthesize_returns_pcm(monkeypatch):
+    _install(monkeypatch, _ok_handler())
+    p = ChatterboxTTSProvider("http://x:9999", voice="/ref.wav")
+    pcm = __import__("asyncio").run(p.synthesize("Hallo Welt"))
+    assert pcm == b"\x01\x02" * 2400  # 24000 Hz -> kein Resampling, Frames unveraendert
+
+
+def test_synthesize_wav_format(monkeypatch):
+    _install(monkeypatch, _ok_handler())
+    p = ChatterboxTTSProvider("http://x:9999")
+    wav = __import__("asyncio").run(p.synthesize("Hallo", audio_format="wav"))
+    assert wav.startswith(b"RIFF") and b"WAVE" in wav[:16]
+
+
+def test_resample_when_rate_differs(monkeypatch):
+    _install(monkeypatch, _ok_handler(wav_rate=22050))
+    p = ChatterboxTTSProvider("http://x:9999", target_rate=24000)
+    pcm = __import__("asyncio").run(p.synthesize("Hallo"))
+    assert isinstance(pcm, bytes) and len(pcm) > 0
+
+
+def test_job_error_raises(monkeypatch):
+    _install(monkeypatch, _ok_handler(status="error"))
+    p = ChatterboxTTSProvider("http://x:9999")
+    with pytest.raises(RuntimeError):
+        __import__("asyncio").run(p.synthesize("Hallo"))
+
+
+def test_empty_text_raises(monkeypatch):
+    p = ChatterboxTTSProvider("http://x:9999")
+    with pytest.raises(ValueError):
+        __import__("asyncio").run(p.synthesize("   "))
+
+
+def test_ref_voice_selection():
+    p = ChatterboxTTSProvider("http://x:9999", voice="/default.wav")
+    assert p._ref_voice(None) == "/default.wav"
+    assert p._ref_voice("Zephyr") == "/default.wav"        # Cloud-Name -> Default
+    assert p._ref_voice("/custom.wav") == "/custom.wav"    # Pfad -> uebernommen