docs: 完善中文README，补充完整本地启动步骤与新手排错方案

[derunzhen]

Summary / 摘要

完善中文README文档，补充完整本地项目启动流程与新手环境报错排错方案，降低新开发者上手门槛。

Motivation / 背景与动机

新用户初次拉取项目后缺少清晰的本地部署指引，容易因未安装pnpm、依赖安装失败等问题无法运行项目，本次补充完整操作步骤提升文档友好度。

• Issue: 无
• Roadmap (docs/ROADMAP.md): 文档优化类需求
• OpenSpec change: 无

Changes / 变更内容

仅修改文档文件，无业务代码改动：

• README.zh.md：新增本地启动教程，包含环境要求、依赖安装、开发启动、打包构建命令与常见问题解决办法

Screenshots / Recordings · 截图或录屏 (UI changes)

无UI界面变更，无需附加截图

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