Allow user shell commands to run alongside active turns

[jif-oai]

Summary

• refactor user shell command execution into a shared helper and add modes for standalone vs active-turn execution
• run user shell commands asynchronously when a turn is already active so they don’t replace or abort the current turn
• extend the tests to cover the new behavior and add the generated Codex environment manifest

Testing

• Not run (not requested)

[jif-oai]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 8622225ae8

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[jif-oai]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: fdd699ef07

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".