fix(team-core): reap 4-line locks whose owner pid is already dead

Pid reuse is not the only Windows hang: when the parked child dies and
the next spawn gets a new pid, detectStaleLock waited 15s because a
fresh dead-pid lock is younger than staleAfterMs. 4-line payloads treat
a dead owner as stale immediately. Legacy 3-line keeps the age rule.