## 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.
