## Why
Release jobs download the `codex-zsh` manifest before packaging or signing its
bundled binaries. Verify that download against a pinned digest so an unexpected
manifest cannot enter release artifacts.
## What changed
- Pin the SHA-256 digest for the `codex-zsh-v0.1.0` manifest.
- Add a portable verification script that uses `sha256sum` or macOS `shasum`.
- Run verification in both the package archive and macOS helper signing flows.
GitOrigin-RevId: a404bb897c8cc0bf3c0ff38e8a6e1cce059d7fab