Agent Skills: plan-task

Plan complex tasks and write structured plan documents to the project's plans/ directory. Use this skill whenever the user asks to plan a task, create a plan, design a solution, make a plan, analyze a requirement before implementation, or says "先规划一下", "先出个方案", "帮我设计", "分析一下怎么做". Also trigger proactively when the user describes a large, ambiguous, or multi-step task that would benefit from upfront planning before any code is written. This skill operates in planning-only mode — it reads code, runs verification commands, and produces plan documents, but MUST NOT write or modify any production code or configuration files.