Prepare Python SDK 0.147.0 stable release (#39155)

## What changed

- Pin `openai-codex` to the `0.147.0` CLI runtime and regenerate its protocol models and lockfile.
- Allow stable Python SDK release tags and require their versions to match the pinned runtime.
- Expose the regenerated API additions, including thread sections, environment connection notifications, audio inputs, and the `section_id` thread-list filter.

## Testing

- Update release staging, generated-contract, notification, and public-signature coverage for the new runtime.

GitOrigin-RevId: 8b99ef6781e01c34d9d697c8c44247fb4e4fe3ab

sdk/python/tests/test_public_api_signatures.py

@@ -339,6 +339,7 @@ def test_generated_public_signatures_are_snake_case_and_typed() -> None:
             "limit",
             "model_providers",
             "search_term",
+            "section_id",
             "sort_direction",
             "sort_key",
             "source_kinds",
@@ -414,6 +415,7 @@ def test_generated_public_signatures_are_snake_case_and_typed() -> None:
             "limit",
             "model_providers",
             "search_term",
+            "section_id",
             "sort_direction",
             "sort_key",
             "source_kinds",