dsh-plugin-playbook: Codify successful tasks into SOPs and delivery gates

The DSH plugin **yangyiqun747/dsh-plugin-playbook** codifies a successful task into a structured playbook (reusable SOP + pitfall checklist), which appears as a native Skill in the skill catalog for on-demand recall when similar tasks arise. With sufficient accumulated samples, it can be upgraded into a delivery gate: requiring user review before execution, obtaining objective evidence item-by-item before delivery, and L2+ will strictly block write/edit/present actions. This article provides a tool list, storage format, recall and fallback rules, gate levels and invariants, official installation command, configuration items, and a complete walkthrough of usage.