docs: add Code Review Rules section for Codex review

AGENTS.md

@@ -0,0 +1,16 @@
+## Code Review Rules
+
+Each line names a rule CI does not enforce; the linked file states it in full.
+
+- Org-wide criteria: [`REVIEW.md`](REVIEW.md), synced from `melodic-software/standards`.
+- Claude lane security model (`SECURITY MODEL` headers):
+  [`claude-review.yml`](.github/workflows/claude-review.yml) and
+  [`claude-security-review.yml`](.github/workflows/claude-security-review.yml).
+- Claude lane checks stay advisory: [rule](README.md#claude-lanes--shared-consumption-contract).
+- Configurable, not forkable: [rule](README.md#contract).
+- Policy is authored in standards; `fixtures/` configs only exercise contracts:
+  [rule](README.md#policy-ownership-and-action-inputs).
+- Local-lane guard wrappers keep parity with the standards component:
+  [rule](docs/topics/local-lane-guards.md).
+- Lanes consolidate as composite actions; `ci-status` stays the single required check:
+  [rule](docs/topics/ci-fanout-consolidation/ADR.md#decisions-locked).