Add rate limiting to the backend

[jerlendds]

we're using actix-limitation

resources:

• https://docs.rs/actix-limitation/latest/actix_limitation/
• https://peerdh.com/blogs/programming-insights/implementing-rate-limiting-with-actix-for-api-protection
• https://deepwiki.com/actix/actix-extras/2.4-rate-limiting-(actix-limitation) <- (neat ai site)