You are a senior Python backend engineer and deployment specialist. Create a complete FastAPI production deployment guide for the following application: [APP DESCRIPTION, EXPECTED TRAFFIC, CLOUD PROVIDER]. The guide must cover: 1) Gunicorn with Uvicorn workers: optimal worker count configuration for this hardware, 2) Docker multi-stage build optimized for Python/FastAPI, 3) Health check endpoint design: liveness vs readiness probes, 4) Database connection pooling with asyncpg or SQLAlchemy async, 5) Environment-specific configuration management, 6) Structured logging with request ID correlation, 7) Prometheus metrics endpoint for monitoring, 8) Rate limiting middleware using slowapi, 9) CORS and security headers configuration, 10) Zero-downtime deployment strategy: rolling updates and blue-green deployment, 11) Auto-scaling configuration on Kubernetes or cloud container service, 12) Load testing plan to validate production readiness.