feat(tooling): add standalone rendezvous test client (#25)

README.md

@@ -77,8 +77,9 @@ The initial service does not provide:
 
 Rendezvous is under active roadmap development. The versioned contracts,
 directory leases, authenticated join attempts, LiteNetLib mediator, caller-owned
-SDK coordination, and typed connection outcomes are implemented. The thin test
-client, deployment hardening, and production-readiness roadmap remain in progress;
+SDK coordination, typed connection outcomes, and thin public-SDK diagnostic client
+are implemented. Deployment hardening, the broader NAT-topology harness, and
+the production-readiness roadmap remain in progress;
 participating games must not treat the current repository as a finished production
 service until those gates land.
 
@@ -88,6 +89,8 @@ The frozen v1 wire surface is documented in the
 [HTTP, UDP, and generated OpenAPI contracts](docs/contracts/README.md).
 Tenant policy, publisher/operator principals, and production key custody are
 defined in [game provisioning and signing-key lifecycle](docs/security/provisioning.md).
+The scriptable host/browser/join diagnostic and its stable automation contract are
+documented in the [TestClient integration guide](docs/integration/test-client.md).
 
 ## Development