Small feature stack

Scenario: add admin-audit-logging without mixing storage, write paths, and UI in one PR.

main
└─ stack/admin-audit-logging-spec
   └─ stack/admin-audit-logging-model
      └─ stack/admin-audit-logging-api

Artifacts to expect: committed spec at docs/specs/admin-audit-logging.md, local plan at .pi/stack-ops/plans/admin-audit-logging.plan.md, validation notes under .pi/stack-ops/validation/.

Use this as a shape check, not a substitute for an approved spec and plan. Start with Quickstart, then use Your first stack for the full walkthrough.