API rate limiting & Validation middleware

Implement API rate limiting and input validation middleware.

**Requirements:**
- Add rate limiting (e.g., 100 requests per 15 minutes per IP)
- Implement input validation for all endpoints
- Add CORS middleware for cross-origin requests
- Implement request logging middleware
- Add request/response compression
- Security headers (X-Frame-Options, X-Content-Type-Options, etc.)

**Deliverables:**
- Rate limiting middleware (express-rate-limit or similar)
- Input validation using Joi or similar library
- CORS configuration
- Request logging setup
- Middleware chain integration in main app