ci: prevent shell injection in bench workflow inputs

[minagishl]

Summary

• Route all workflow_dispatch inputs in the benchmark step through environment variables instead of interpolating them directly into the shell script.
• Validate time_ms and warmup_ms as positive integers before invoking the benchmark.

This closes a script-injection vector where malicious time_ms or warmup_ms values could inject arbitrary shell commands or CLI flags when the workflow is triggered via workflow_dispatch.

Related Issue

Closes #1

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation
• Chore / dependency update

Testing

• Verified the workflow YAML structure is valid.
• Confirmed time_ms / warmup_ms validation rejects non-integer values before tsx is invoked.
• Confirmed all inputs (backend, mode, time_ms, warmup_ms, twilic_vs_msgpack_only) are passed via env vars and referenced with quoted shell expansions.

Checklist

• Tests added or updated (optional)
• Documentation updated (if applicable)
• No breaking changes (or breaking changes are documented above)

[github-actions]

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No suspicious invisible characters detected in the PR diff.

[cursor]

Risk: low. Approved — Cursor Bugbot was not present on this PR; the bench workflow change routes dispatch inputs through env vars with integer validation for timing fields, which addresses the injection vector. No reviewers assigned.

  

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