Block a user
fleetd #511: fix wrong --no-build wording in drain-gate abort, pin jar_id() default
fleetd #493: never build into the path a running daemon holds
fleetd #505: refuse (not promote) a caller whose pane scan errored
fleetd #501: readiness-grace expiry logs measured elapsed time and poll counter
fleetd #498: awaitHerdr distinguishes deadline-passed from interrupted, with measured elapsed time
fleetd #492 follow-up: detect_supervisor must never read "could not tell" as "none"