## Why
Allow remote exec-server registration to use credentials independently of Codex login while retaining the usual local configuration and plugins.
## What changed
- Add `--registration-bearer-stdin` to read one newline-terminated bearer and use it for remote registration.
- Validate the bearer, require HTTPS or HTTP loopback for the registry, and disable process dumpability on Linux before reading the credential.
- Document the option and its distinction from rotating credentials via `--executor-credential-stdin`.
## Testing
Add integration coverage for registration with the supplied bearer across desktop sign-in states, rejection of non-loopback HTTP registries, and restricted process environment access on Linux. Update CLI help snapshots.
GitOrigin-RevId: da99492270c5dc6bb5e0cac41947e9c999a72b75