[Colin4k1024]

What changed

• Upgrade the existing Loop Engineering draft into an active Chinese user runbook.
• Document capability boundaries, installation, loop spec configuration, command workflows, state recovery, safety controls, and troubleshooting.
• Add the runbook to the user-guide navigation.

Why

The recently added Loop Engineering runtime had implementation and command documentation, but lacked a complete user-facing guide that explained when to use it and how to operate it safely across supported targets.

User impact

Users now have an executable onboarding path for /loop-start, /goal, /heartbeat, /triage, /loop-status, and related state management. The guide also clarifies that Loop Engineering is a beta capability pack rather than a ninth team role.

Validation

• Markdown lint on both changed files
• node scripts/validate-file-references.js --strict
• node scripts/validate-doc-freshness.js
• node scripts/validate-library.js
• Loop spec parser smoke test
• Codex selective install-plan verification for loop-engineering