Function build_admin_router 

pub fn build_admin_router(state: AppState) -> Router

The private/admin router (used in public/private split mode): the internal ops endpoints (health, readiness, metrics). It has no proxy fallback, so an unknown path returns 404 rather than being forwarded upstream. Shares the same AppState as the public router, so /__edgeguard/metrics reports the live proxy counters.