feat: scaffold stentor-gateway with FastAPI voice pipeline

Initialize the stentor-gateway project with WebSocket-based voice
pipeline orchestrating STT → Agent → TTS via OpenAI-compatible APIs.

- Add FastAPI app with WebSocket endpoint for audio streaming
- Add pipeline orchestration (stt_client, tts_client, agent_client)
- Add Pydantic Settings configuration and message models
- Add audio utilities for PCM/WAV conversion and resampling
- Add health check endpoints
- Add Dockerfile and pyproject.toml with dependencies
- Add initial test suite (pipeline, STT, TTS, WebSocket)
- Add comprehensive README covering gateway and ESP32 ear design
- Clean up .gitignore for Python/uv project

stentor-gateway/Dockerfile

@@ -0,0 +1,49 @@
+# Stentor Gateway — Multi-stage Dockerfile
+# Builds a minimal production image for the voice gateway.
+
+# --- Build stage ---
+FROM python:3.12-slim AS builder
+
+WORKDIR /build
+
+# Install uv for fast dependency resolution
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+
+# Copy project files
+COPY pyproject.toml .
+COPY src/ src/
+
+# Install dependencies into a virtual environment
+RUN uv venv /opt/venv && \
+    uv pip install --python /opt/venv/bin/python . --no-cache
+
+# --- Runtime stage ---
+FROM python:3.12-slim AS runtime
+
+LABEL maintainer="robert"
+LABEL description="Stentor Gateway — Voice gateway for AI agents"
+LABEL version="0.1.0"
+
+# Copy virtual environment from builder
+COPY --from=builder /opt/venv /opt/venv
+
+# Copy application source (for templates/static)
+COPY src/ /app/src/
+
+WORKDIR /app
+
+# Use the venv Python
+ENV PATH="/opt/venv/bin:$PATH"
+ENV PYTHONPATH="/app/src"
+ENV PYTHONUNBUFFERED=1
+
+# Default configuration
+ENV STENTOR_HOST=0.0.0.0
+ENV STENTOR_PORT=8600
+
+EXPOSE 8600
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+    CMD python -c "import httpx; r = httpx.get('http://localhost:8600/api/live/'); r.raise_for_status()"
+
+CMD ["uvicorn", "stentor.main:app", "--host", "0.0.0.0", "--port", "8600"]