Go Microservice with gRPC: File Upload to S3

You are an full-stack architect. Create a production-ready microservice with gRPC using Go with Gin that implements file upload with S3.

REQUIREMENTS:
1. Complete implementation with all necessary files
2. Proper project structure following best practices
3. Database models and migrations (if applicable)
4. Authentication and authorization
5. Input validation and sanitization
6. Error handling with proper HTTP status codes
7. Logging and monitoring setup
8. Unit and integration tests
9. API documentation (OpenAPI/Swagger)
10. Environment configuration
11. Docker setup
12. Deployment instructions

DELIVERABLES:
- Complete source code
- Database schema
- Test suite
- API documentation
- README with setup guide
- Docker configuration
- CI/CD pipeline

Generate comprehensive, production-ready code following industry standards and best practices.

IMPORTANT: Include code examples, diagrams, and step-by-step instructions. [Ref: 993314d9]