CVE vulnerability response playbook: closed-loop checklist from alert to fix

CVE vulnerability response playbook: break T0 disclosure, T1 impact triage, T2 gate enforcement, and T3 backlog remediation into roles, SLAs, and checklists. For security ops and SREs—turn alerts into a measurable loop and shrink the window known risk still enters builds. Confirm details against official docs and the current product version.