Contract First Planner — 契约先行

This skill should be used before writing code for any multi-module, multi-file, or client/server feature. It produces and freezes one authoritative data-model + inter-module interface contract that becomes the single source of truth for all subsequent code generation. Triggers include: '开始开发 / 从零搭建 / 搭个架子 / 新项目开工 / 多模块 / 前后端 / 定接口 / 接口设计 / API 设计 / 定义数据模型 / 数据结构设计 / 设计 schema / 表结构 / 模块划分 / 契约先行 / 先定协议 / 冻结接口 / 字段对不齐 / 联调对不上 / 接口不一致 / 改一处崩一片 / design the data model / define the API contract / interface spec / schema first / contract first / freeze the interface / plan modules before coding'. Workflow: scope detection → requirement elicitation → data modeling → module & in…