Add a config option to disable the update check (and version upgrade prompt) for better central management

What feature would you like to see?

I manage the distribution of AI tooling to developers in a larger engineering org. We're starting to distribute Codex CLI, but we prefer to centrally manage updates ourselves, rather than ending up with everyone on various versions, managing updating themselves, and so on.

Currently, though, Codex will immediately suggest for users to update, once a new version is published:

✨⬆️ Update available! [X] -> [Y].
[Instructions...]

So the request is to give us a config option that we can set for folks to disable these checks to reduce confusion.

Are you interested in implementing this feature?

Would love to. This seems like a fairly trivial change, I have a change ready but I'm waiting for the ack on this issue per contributing guidelines: https://github.com/byrongrogan/codex/pull/1

Additional information

_No response_