[advisory:implementation-status] Reconcile UK AI advisory ledger with 2026-05-14 GOV.UK guidance
Changed requirement IDs and source dates: Added UK-AI-016 (safe posture for unmaintained code) from the current GOV.UK guidance published 2026-05-14 and verified 2026-08-29. Added UK-AI-017 (avoid private-by-default drift) from the current GOV.UK guidance published 2026-05-14 and verified 2026-08-29. Updated the verification date on UK-AI-015 because the ledger changed materially in this same audit. Summary: Reconciled .github/workflows/uk-ai-advisory.md and .github/workflows/advisory-uk-ai-operational-resilience.md against the current authoritative GOV.UK guidance. Recorded a PARTIAL gap for explicit assessment of dormant/unmaintained repository posture, including archive marking and own...