init supervises its boot services (spawned against an exit endpoint) but the
child-exit handler was `if (got.isNotification()) continue;` — it silently
dropped a dead service. Now init restarts it: on a child-exit notification it
finds the service, and unless it exited cleanly (chose to stop) or has hit the
crash-loop cap (maximum_restarts), respawns it and logs the death + reason. The
reincarnation half of resilience (docs/resilience.md) at the service level, the
counterpart to the device manager's driver restarts. A `shutting_down` flag
skips restarts during the orderly stop sequence, whose child deaths are expected.