CBox Process: hard-block PR when cbox review runtime is missing

Problem

The /pr workflow in cbox sandboxes offers a "skip review and open PR" menu option when Docker/Podman is not available for cbox review. During the M1-INFRA-027 incident, an agent selected this skip path, resulting in PR #441 being opened without any code review. This violates the project's mandatory review-before-PR policy and undermines the entire quality gate. The auto-skip menu should not exist as a default path — missing review runtime should be a hard blocker that requires explicit human override in the current conversation thread, not a silent menu choice an agent can select autonomously.

Context

Possible Solutions

Plan

Implementation Progress

• Closed 2026-03-04: implemented in PR #447 (commit e1cf6204). Hard-block logic in container.py prevents PR flow when Docker/Podman is missing.

Review Feedback

• Review cleared