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/pyproject.toml

@@ -0,0 +1,45 @@
+[project]
+name = "stentor-gateway"
+version = "0.1.0"
+description = "Voice gateway connecting ESP32 audio hardware to AI agents via speech services"
+requires-python = ">=3.12"
+license = "MIT"
+dependencies = [
+    "fastapi>=0.115",
+    "uvicorn[standard]>=0.34",
+    "websockets>=14.0",
+    "httpx>=0.28",
+    "pydantic>=2.10",
+    "pydantic-settings>=2.7",
+    "jinja2>=3.1",
+    "prometheus-client>=0.21",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.0",
+    "pytest-asyncio>=0.25",
+    "pytest-httpx>=0.35",
+    "ruff>=0.9",
+]
+
+[project.scripts]
+stentor = "stentor.main:main"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/stentor"]
+
+[tool.ruff]
+target-version = "py312"
+line-length = 100
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "N", "W", "UP", "B", "SIM", "RUF"]
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["tests"]