feat: add Dockerfile with CPU-only torch, .dockerignore, and requirements-cpu.txt

- Multi-stage Dockerfile with CPU-only PyTorch
- .dockerignore to exclude build artifacts
- requirements-cpu.txt for CPU-only dependencies
- Health check endpoint for container monitoring

requirements-cpu.txt

@@ -0,0 +1,26 @@
+# WebSocket server
+fastapi
+uvicorn[standard]
+websockets
+webrtcvad
+
+# Speech-to-Text
+faster-whisper
+soundfile
+
+# LLM (CPU-only)
+transformers
+accelerate
+bitsandbytes
+
+# TTS
+torchaudio
+
+# Audio processing
+numpy
+scipy
+
+# Utilities
+python-dotenv
+pydantic
+pydantic-settings