Implement the engine spine: claim, outbox, machine, API

Contracts first (T02–T04): approval claim schema with issuer, freshness,
and binding digest; local transactional outbox wire; load-bearing cadence
as heartbeat or reconciliation (layer.yaml declared).

Then the object (T06–T08): SQLite closed state machine, CAS supersession,
distinct-approver fail-closed, revocation without holder cooperation,
outbox insert in the same transaction. Tests fail the mutation when
emission fails, and revoke while the drain sink is down.

Introspection GET /v1/approvals/{id}/claim is a PIP fact, not a decision.
No public consume (T05 waits on GH-WP-0002-T06). Canon T-06 coverage for
wrong binding, expiry, revoke, and supersede.

FLEX-WP-0017 T03 is unblocked on this object; T05 remains blocked only on
consumption ordering.

Assistant: grok
Assistant-Session: 01a04ceb-2057-7e20-b0f9-c282964d5dd9

Makefile

@@ -0,0 +1,11 @@
+SHELL := /usr/bin/env bash
+.DEFAULT_GOAL := test
+
+test: ## Run unit tests
+	python3 -m pytest -q
+
+help: ## Show this help
+	@awk 'BEGIN {FS = ":.*##"; printf "\nUsage:\n  make \033[36m<target>\033[0m\n"} \
+	  /^[a-zA-Z_-]+:.*?##/ { printf "  \033[36m%-24s\033[0m %s\n", $$1, $$2 }' $(MAKEFILE_LIST)
+
+.PHONY: test help