Initial voice-assistant-stack: open-webui + spotify-voice-assistant submodules, asr/tts sidecars

- open-webui: submodule, LAN OIDC/Authentik-fronted, GPU-passthrough ollama,
  ollama-auth proxy, asr/tts wired via docker-compose.audio.yaml
- spotify-voice-assistant: submodule, Home Assistant custom integration
- tts-server / asr-server: plain directories, built as sidecars by
  open-webui/docker-stack.sh (no separate git history)

tts-server/Dockerfile

@@ -0,0 +1,17 @@
+FROM python:3.11-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libsndfile1 ffmpeg espeak-ng \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+# The Titan Xp (Pascal, sm_61) needs a torch build old enough to still ship
+# Pascal kernels; recent default PyPI wheels dropped sm_60/sm_61 entirely.
+ENV PIP_EXTRA_INDEX_URL=https://download.pytorch.org/whl/cu121
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY app.py .
+
+EXPOSE 8010
+CMD ["uvicorn", "app:app", "--host", "0.0.0.0", "--port", "8010"]