Generate Python SDK types from pinned runtime

Make the SDK artifact generator fetch schema from the pinned runtime package, regenerate the checked-in Python types from that schema, and assert generated artifacts stay up to date.

Co-authored-by: Codex <noreply@openai.com>

sdk/python/tests/test_client_rpc_methods.py

@@ -66,6 +66,7 @@ def test_thread_resume_response_accepts_auto_review_reviewer() -> None:
                 "id": "thread-1",
                 "modelProvider": "openai",
                 "preview": "",
+                "sessionId": "session-1",
                 "source": "cli",
                 "status": {"type": "idle"},
                 "turns": [],