Remove security and rate limiting middleware from backend

- Removed security middleware setup from main.py
- Disabled security middleware functionality
- Removed rate limiting middleware setup

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/main.py

@@ -135,13 +135,9 @@ app.add_middleware(
 # Add analytics middleware
 setup_analytics_middleware(app)
 
-# Add security middleware
-from app.middleware.security import setup_security_middleware
-setup_security_middleware(app, enabled=settings.API_SECURITY_ENABLED)
+# Security middleware disabled - handled externally
 
-# Add rate limiting middleware only for specific endpoints
-from app.middleware.rate_limiting import RateLimitMiddleware
-app.add_middleware(RateLimitMiddleware)
+# Rate limiting middleware disabled - handled externally
 
 
 # Exception handlers