Code-review follow-up to cf0101be7. The merger integration worktree path
was still calling bare `activeSessionRegistry.reconcileStaleSelfOwned` for
same-task entries, bypassing the minIdleMs window introduced by the main
fix. A merger-handoff that races a warming-down session could clear a
registry entry < 5s old. Route through `reconcileSelfOwnedActiveSessionForRemoval`
with the `executingTaskLock` process probe so all reconcile sites enforce
the same liveness contract. Test updated to backdate `registeredAt`,
matching the pattern used for the other reliability-interactions tests.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
b4fc54bb20