Function rate_limit 

pub async fn rate_limit(
    __arg0: State<Arc<ServerState>>,
    __arg1: ConnectInfo<SocketAddr>,
    limiter: Extension<Arc<AuthRateLimiter>>,
    request: Request,
    next: Next,
) -> Response

Per-source-IP rate-limit middleware for the /api/v1/auth/* sub-router. Reads super::ServerState::auth_rate_limit_per_minute; when None, the middleware is a no-op (operators rate-limit at the proxy). When the per-IP request count exceeds the limit, returns 429 Too Many Requests with an ErrorResponse body and a tracing::warn! event.