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

pyproject.toml

@@ -0,0 +1,16 @@
+[project]
+name = "approval-engine"
+version = "0.1.0"
+description = "PIP for the approval object: durable, authenticated, consumable, atomically supersedable."
+readme = "README.md"
+requires-python = ">=3.11"
+
+[project.optional-dependencies]
+dev = ["pytest"]
+
+[project.scripts]
+approval-engine = "approval_engine.cli:main"
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+pythonpath = ["."]