Keep Agents And README Fresh

Install the canonical Documentation Freshness policy into existing agent instruction files. This is an additive, one-time setup task.

Canonical Section

## Documentation Freshness

Repo reality is the source of truth. If `AGENTS.md` or `README.md` becomes false, update it in the same change when the fix is objective.

Objective facts include repo structure, tracked paths, setup commands, validation commands, runtime/tooling, skill/resource/prompt inventory, and workflow constraints proven by the repo.