API Rate Limits

What is the current rate limiting scheme on the Keybase API? e.g., Requests/second, burst queueing, rate limit headers, etc.

I found a previous issue (#1804) that talks about the nginix config in use, but it's a few months old and isn't really clear on what the API is configured for. The comment that it `doesn't explicitly specify rate` is odd given that the nginx docs seem to assume `rate` is set to some value in the config (or at least I can't find a default value for it).

Start by reviewing issue #1804 and the nginx configuration it references. Verify the API's requests-per-second limit, burst behavior, and rate-limit headers from the current configuration or maintainer-confirmed settings. Done means documenting the current scheme and clarifying whether nginx applies an explicit rate.

Written by the indexing model from the issue text.