fix(windows-sandbox): remove request files after read

[MaxMiksa]

Summary

• Remove elevated runner request files after read (best-effort cleanup on errors)
• Add a unit test to cover request file lifecycle

Testing

• cargo test -p codex-windows-sandbox (Windows)

Fixes #9315

[github-actions]

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[MaxMiksa]

I have read the CLA Document and I hereby sign the CLA

[etraut-openai]

@codex review

[chatgpt-codex-connector]

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Reviewed commit: d3b8a8d481

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[MaxMiksa]

Updated the test to use pretty_assertions::assert_eq as suggested and re-ran cargo test -p codex-windows-sandbox on Windows (pass).

[MaxMiksa]

Thanks @etraut-openai for the codex review. I just merged the latest main into this branch to clear the out-of-date warning, which re-triggered CI. In prior runs, the only failures were Bazel (experimental) due to missing API keys in the fork (BEP upload). Happy to rerun or adjust if you need anything.

[iceweasel-oai]

thanks for doing this!