feat(policy): add credential grant authorization package

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a02e47-6aac-7ee1-914d-0584c75d3c81

examples/railiance-platform/check_request_allow.json

@@ -0,0 +1,21 @@
+{
+  "id": "check:credential-grant-allow-http-shape",
+  "tenant": "tenant:platform",
+  "subject": {
+    "id": "agent:codex/railiance-platform",
+    "type": "Agent"
+  },
+  "action": "issue",
+  "resource": {
+    "id": "credential-grant:rapp-postgres/audit-core-runtime",
+    "type": "credential-grant",
+    "system": "railiance-platform"
+  },
+  "context": {
+    "actor_type": "approved-agent",
+    "bound_subject": "agent:codex/railiance-platform",
+    "purpose": "audit-core-runtime",
+    "delivery_mode": "exec-env",
+    "requested_ttl_seconds": 900
+  }
+}