## Why
The macOS release workflow fetched `rg` and zsh while assembling package
archives, after the signing stage. This left the bundled helper executables
outside the workflow's signing and notarization checks.
## What changed
- Fetch, sign, notarize, and upload the pinned macOS `rg` and zsh binaries with
the other release artifacts.
- Build package archives from those signed helpers via `--rg-bin` and the new
`--zsh-bin` override.
- Verify the helpers' architecture, signatures, and absence of entitlements in
the final package.
## Testing
- Cover the prebuilt zsh override and verify that package assembly preserves
the supplied helper binaries.
GitOrigin-RevId: a3865c04fa2f0f4df32e627ee7202bc87bdc3241
## Summary
- build, strip, sign, and publish `codex-code-mode-host` with the
primary Codex release binaries on Linux, macOS, and Windows
- place the host beside `codex[.exe]` in canonical package archives,
macOS DMGs, and the legacy Linux bundle so the runtime's sibling lookup
succeeds
- preserve and validate the host through standalone installers and
Python runtime wheel staging
- add package-builder coverage for source selection and the resulting
package layout
## Why
The process-owned code-mode client launches `codex-code-mode-host` as a
sibling of the running Codex executable. Release artifacts currently
build and bundle `codex` without that host, so code mode cannot start
from installed packages.
