Harden the Codex app-server native execution bridge for OpenClaw sandboxed runs. The change keeps core sandbox policy in OpenClaw while exposing the process, filesystem, and HTTP relay behavior Codex needs inside a scoped exec server.
The large exec-server/test files were split into focused modules before landing, and the PR was rebased onto current main with focused tests, Testbox changed checks, CI, and Codex autoreview green.
Co-authored-by: joshavant <830519+joshavant@users.noreply.github.com>