[Security] Add rate limiting to authentication routes to prevent brute-force abuse

[mohdsubhan1756]

Authentication routes are currently accessible without rate limiting, while other API routes already use generalLimiter. This increases the risk of brute-force login attempts, repeated registration spam, and abuse of authentication endpoints.

[mohdsubhan1756]

Hi,
I would like to fix this issue under GSSOC 2026.
Please assign this to me.
Thank you.