feat: Complete Docker implementation for SafePathAI

[Raghurajpratapsingh28]

🐳 Docker Implementation Features:
Solves #34

• Added comprehensive Docker configuration for both frontend and backend
• Created docker-compose.yml for development environment
• Added docker-compose.prod.yml for production deployment
• Implemented multi-stage builds for optimized container images
• Added security best practices (non-root users, health checks)
• Created comprehensive documentation and setup guides

📁 Files Added:

• docker-compose.yml & docker-compose.prod.yml
• backend/Dockerfile & frontend/Dockerfile
• backend/.dockerignore & frontend/.dockerignore
• frontend/nginx.conf for optimized serving
• backend/env.example for environment configuration
• DOCKER.md & DOCKER_IMPLEMENTATION.md documentation
• test-docker-setup.sh validation script
• Updated README.md with Docker setup instructions

🚀 Quick Start:

1. cp backend/env.example backend/.env
2. docker-compose up -d
3. Access at http://localhost:3000

✅ Benefits:

• Consistent development environment
• Easy deployment and scaling
• Production-ready configuration
• Comprehensive documentation
• Security best practices implemented

[SrinjoyeeDey]

Hii @Raghurajpratapsingh28 , i am reviewing your PR , it might take few days , within 3 days I will merge it , Thank You for contributing