Support tracing the OpenAI Codex SDK

[jonahsnider]

OpenAI has an SDK specifically for using Codex programmatically: @openai/codex-sdk for JS and an experimental Python implementation.

It'd be nice if the Braintrust SDK was able to wrap the Codex SDK and provide tracing, the same way it currently supports the OpenAI Agents SDK.

See also: https://developers.openai.com/codex/sdk

[AbhiPrasad]

thanks for the issue Jonah Snider (@jonahsnider)! we'll backlog this, but this is definitely something we'll look to do!