docs(rescue): document writable sandbox scope

[rksharma-owg]

Summary

• document that write-capable rescue runs are limited to the current repository and temporary directories
• recommend staging artifacts in the repository when their final destination is a home, configuration, or system path
• keep the user-facing README, rescue agent, and runtime guidance aligned

Testing

• npm test (91 tests passed)
• npm run build
• npm run check-version
• git diff --check

Fixes #673

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-04T01:04:45.108826Z	9d67a92	Manual request

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[rksharma-owg]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Hooray!

Reviewed commit: 9d67a92047

ℹ️ About Codex in GitHub

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• 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 👍.

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