Rate Limiting Middleware

Summary

Middleware (like `express-rate-limit`) that caps how many requests a client can make in a time window — protects your API from abuse and accidental overload.

• 1Add rate limiting to a login endpoint to slow down brute-force attempts.
• 2Configure different rate limits for authenticated vs unauthenticated requests.
• 3Learn how rate limiting interacts with running multiple server instances — it needs shared storage like Redis.