Documentation subtree rules

Read docs/authority.toml before treating a document as current.
Canonical docs describe current behavior; active plans describe incomplete work; accepted ADRs describe decisions and constraints; evaluations describe dated evidence.
Historical and superseded documents are not current requirements.
Do not duplicate detailed contracts across README, guides, plans, ADRs, and tracker bodies.
Update the smallest canonical surface that owns the changed behavior.
Run scripts/codex/docs_audit.py through the documentation-integrity workflow.