nx_daemon_reap_gate.nx

nx_daemon_reap_gate.nx -- referee for nx_daemon_reap_lib, the ONE child reaper every forking daemon in the estate should compose. It gates the SAME functions a daemon would run, not a reimplementation, and it reaps REAL children it forks itself -- a reaper proven only on synthetic inputs has never met wait4. THE TEETH THAT MATTER: T1 is the empty-set case, and it is not decoration: a drain called with no children must RETURN, not block. Getting WNOHANG wrong turns every idle accept loop in the estate into a hang. T3 proves reaping actually happens against children this gate created, so a pass cannot come from a function that quietly does nothing -- the exact vacuity that let sixteen daemons leak for weeks. T6/T7 are the counter-underflow guard. A live-child counter that goes NEGATIVE turns a concurrency cap into a permanent grant, and that failure direction is silent: the daemon keeps serving, keeps forking, and nothing looks wrong until the box is the thing that reports it. T5 neg-control: below the cap the throttle must NOT wait. A throttle that always blocks would pass every "did it reap?" tooth while serialising the whole server. T8 bite: the drain FIRES on an exited child and stays SILENT when there is none, in one cell. license_tier: ORIGINAL expect_exit: 0