docs: record sustained replay drains

[kim-em]

Updates the mutable overhaul runbook to the current replay posture:

• records the reviewed terminal private proof and cleanup binding;
• records both bounded sustained lanes as active;
• splits completed private activation from the still-open queue drain; and
• updates the compact current-state blocker.

This changes current operational status only and adds no run history or product scope.

Local checks: git diff --check; workflow action-pin audit.