ci: satisfy hotpath workflow lint

[BleedingDev]

Summary

• separate command substitution from exported variables so shell failures stay visible
• pass the PR head ref through an environment variable before shell interpolation
• preserve the existing hotpath workflow behavior

Why

The two hotpath workflows contained actionlint and ShellCheck violations that could hide failed substitutions and interpolate GitHub input directly inside shell source.

Verification

• actionlint passes for all 10 workflow files
• aggregate Rustfmt and diff checks pass
• branch scope audit: one commit, two workflow files, clean worktree

Supports #707.

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Latest commit: a5de55a

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[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 2026-08-30T15:31:39.291732Z	a5de55a	PR opened

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