[codex] Pin Python SDK to runtime 0.137.0a4 (#26216)

## Summary
- pin the Python SDK runtime to `openai-codex-cli-bin==0.137.0a4`
- refresh generated protocol artifacts from `rust-v0.137.0-alpha.4`
- refresh `sdk/python/uv.lock` with all eight published runtime wheels

## Runtime publication
- published `openai-codex-cli-bin==0.137.0a4` through the
`python-sdk-release` workflow
- includes macOS, manylinux, musllinux, and Windows wheels
- publication run:
https://github.com/openai/codex/actions/runs/26905608531

## Validation
- ran `just fmt`
- generated artifacts from the `rust-v0.137.0-alpha.4` release wheel
- ran `uv lock --check --default-index https://pypi.org/simple`
- did not run tests locally, per request; CI provides the test signal

sdk/python/tests/test_contract_generation.py

@@ -40,7 +40,7 @@ def test_generated_files_are_up_to_date():
 
     # Regenerate contract artifacts via the pinned runtime package, not a local
     # app-server binary from the checkout or CI environment.
-    assert importlib.metadata.version("openai-codex-cli-bin") == "0.136.0"
+    assert importlib.metadata.version("openai-codex-cli-bin") == "0.137.0a4"
     env = os.environ.copy()
     env.pop("CODEX_EXEC_PATH", None)
     python_bin = str(Path(sys.executable).parent)