Implement approval engine production readiness

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a05e2e-805b-7042-a750-71f473bceea2

tests/test_api.py

@@ -127,13 +127,29 @@ def test_claim_after_revoke(app):
 
 def test_store_unavailable_is_503():
     from approval_engine.api import App
+    from approval_engine.auth import Identity, StaticTokenAuthenticator
     from approval_engine.errors import StoreUnavailable
     from approval_engine.store import Engine
 
     class Dead(Engine):
+        def storage_status(self):
+            return {"schema_current": True, "persistent": True}
+
         def outbox_stats(self):
             raise StoreUnavailable("down")
 
-    status, body = call(App(Dead.__new__(Dead)), "GET", "/v1/readyz")
+    identity = Identity(
+        subject="test",
+        issuer="test",
+        audiences=("approval-engine",),
+        principal_type="service",
+        tenant="test",
+        roles=frozenset(),
+        scopes=frozenset(),
+        assurance={},
+        evidence_ref="test",
+    )
+    app = App(Dead.__new__(Dead), StaticTokenAuthenticator({"test-token": identity}))
+    status, body = call(app, "GET", "/v1/readyz")
     assert status == 503
     assert body["error"] == "store_unavailable"