[Archive-000]

PR Summary closes #618

Implemented rate-limiting and bounded repeated guesses against the email-verification and password-reset OTP endpoints to prevent brute-force attacks and abuse.

Changes & Implementation closes #616

• Attempt Window & Throttling (auth.service.ts, auth.controller.ts):
• Defined a per-identity attempt window and tracking mechanism for OTP verifications.
• Configured a consistent throttling response (e.g., standard HTTP status and error message) when attempt limits are exceeded.

Scope closes #615

• backend/src/auth/auth.controller.ts
• backend/src/auth/auth.service.ts
• backend/src/auth/auth.service.spec.ts

Testing Instructions closes #617

1. Trigger multiple failed OTP attempts for a specific email/identity on the password-reset or email-verification endpoints.
2. Verify that subsequent attempts within the window return the expected consistent throttling response.
3. Verify that attempt counters successfully reset or expire after the defined time window elapses.
4. Run unit tests locally:

npm test -- backend/src/auth/auth.service.spec.ts