Add unit tests for the request rate limiter correctly blocking requests after the limit is exceeded

[Chucks1093]

Summary

The rate limiter allows N requests per wallet per 60-second window and blocks subsequent requests with a 429. Unit tests should confirm the limiter counts correctly, resets after the window, and includes the correct Retry-After header on blocked responses.

Scope

• Test N requests within the window all succeed (200)
• Test the N+1th request is blocked with 429
• Test the response includes a Retry-After header with the correct seconds remaining
• Test a request from a different wallet is not affected by another wallet's limit
• Test the counter resets and the next request succeeds after the window expires

Acceptance Criteria

• N requests within window succeed
• N+1th request returns 429
• Retry-After header present and correct on 429 response
• Different wallets have independent counters
• Counter resets after the 60-second window

ETA: 12 hours

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Coordinate on Telegram

[GazzyLee]

heelo, I'd love to work on this, ETD is in 6 hours tops, please assign