fix(overpass): keep proxied traffic out of the direct-loopback admission reserve; keep a measured arrival-angle failure through a reveal timeout

- /api/overpass: a loopback socket with forwarding headers (a local reverse
  proxy) is admitted from the remote pool under a socket-keyed proxied: bucket,
  never the owner's direct-loopback window; the upstream limiter uses the same
  key. Regression: owner cache hits survive an exhausted proxy bucket.
- Arrival check: a reveal timeout keeps the settle angle it measured; the new
  observeArrivalRotationWithRetry retries only inconclusive timeouts, so a
  real violation cannot be retried into a pass. Regression: wrong settle angle
  -> reveal timeout -> clean second attempt still fails.
- SECURITY.md, README, changelog and CURRENT-STATE: scope the guarantee to
  admission isolation, name the forwarding headers a local proxy must send,
  and state that the upstream budget stays shared.

README.md

@@ -197,7 +197,7 @@ env UID=1026 GID=100 docker compose up -d
 
 Keep the `env`: bash treats `UID` as read-only, so a plain `UID=1026` in front of a command is silently ignored. If the container can't write the checkout, it says so at start. Docker Desktop on macOS and Windows maps ownership for you.
 
-Behind a reverse proxy, put your keys in `.env` or pass them as environment variables - Provider Settings refuses proxied requests on purpose - and add the hostname you serve it on, for example `GEV_ALLOWED_HOSTS=globe.example.lan` (see [Sharing an instance](#-sharing-an-instance)).
+Behind a reverse proxy, put your keys in `.env` or pass them as environment variables - Provider Settings refuses proxied requests on purpose - and add the hostname you serve it on, for example `GEV_ALLOWED_HOSTS=globe.example.lan` (see [Sharing an instance](#-sharing-an-instance)). If the proxy runs on the same machine, make it send a forwarding header such as `X-Forwarded-For` (Caddy does by default; nginx needs `proxy_set_header`), so its users are rate-limited apart from your own browser.
 
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