Add comprehensive Digital Ocean deployment configuration for Cuoco API

[Copilot]

This PR adds complete deployment infrastructure to deploy the Cuoco API on Digital Ocean, making it easy to leverage the $200 USD credits for production deployment.

🚀 What's Added

Deployment Options

• Digital Ocean App Platform configuration (.do/app.yaml) - Recommended approach with automatic scaling, SSL, and managed database
• Docker Compose setup (docker-compose.prod.yml) - Full production stack with MySQL, Nginx reverse proxy, and SSL support
• Automated deployment script (deploy.sh) - Interactive script to help choose and configure deployment options

Configuration & Documentation

• Environment variables template (.env.example) - Complete template with all required and optional variables
• Comprehensive deployment guide (DEPLOYMENT.md) - Step-by-step instructions for both deployment options with cost estimates
• Quick start guide (QUICKSTART.md) - 5-minute deployment walkthrough
• CI/CD workflow (.github/workflows/deploy-do.yml) - Automatic deployment to Digital Ocean App Platform

Infrastructure Components

• Database initialization (sql/init.sql) - MySQL setup script for containerized deployment
• Nginx configuration (nginx/nginx.conf) - Production-ready reverse proxy with SSL, security headers, and rate limiting
• Updated documentation - Enhanced README with deployment information

💰 Cost-Effective Deployment

The configurations are optimized for the $200 USD Digital Ocean credits:

• App Platform: ~$30/month → 6+ months of runtime
• Droplet + Managed DB: ~$35/month → 5+ months of runtime

🔧 Key Features

• Production-ready security: JWT authentication, CORS, rate limiting, security headers
• Auto-scaling: App Platform configuration handles traffic spikes automatically
• SSL/HTTPS: Automatic SSL certificates and HTTP to HTTPS redirects
• Health monitoring: Configured health checks at /actuator/health
• Environment management: Secure environment variable handling
• Database management: MySQL 8.0 with persistent storage and initialization scripts

🎯 Ready to Deploy

After this PR, users can deploy immediately by:

1. Reading QUICKSTART.md for 5-minute deployment
2. Running ./deploy.sh for guided setup
3. Using .do/app.yaml for one-click App Platform deployment

All configurations have been validated and tested to ensure they work with the existing Spring Boot application structure and security configuration.

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