/metrics is behind a password, and REPO_POLICIES.md requires rate
limiting on password logins. Each client address may now send it 30
requests a minute, counted by httprate before Basic Auth, so failed
logins use up the allowance and a request over it gets 429 without
the password being checked. The address is the one the existing
trusted-proxy logic in internal/middleware works out, with IPv6
addresses grouped by /64; an IPv4 address a proxy reports in
IPv6-mapped form counts as the plain IPv4 address. A Prometheus
server scraping every 15 seconds sends 4 requests a minute.
Model: opus-5-5
