feat: add VChart Skill usage tutorial and navigation entry

[xuefei1313]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
• TypeScript definition update
• Bundle size optimization
• Performance optimization
• Enhancement feature
• Refactoring
• Update dependency
• Code style optimization
• Test Case
• Branch merge
• Release
• Site / documentation update
• Demo update
• Workflow
• Other (about what?)

🔗 Related issue link

🔗 Related PR link

🐞 Bugserver case id

💡 Background and solution

在 VChart 文档站新增一篇“VChart Skill 使用”教程，并将其挂载到与“快速上手”同级的导航层级。教程以用户提供的参考正文为语义来源，覆盖技能简介、安装方式、编辑器适配（Cursor/Trae）以及三个可执行场景（生成简单图表、调整图表样式、修复配置问题），同时保持与现有文档规范一致。

Language/Version: Markdown + JSON（文档内容与菜单配置）
Primary Dependencies: @internal/docs 文档构建体系、docs/assets/guide/menu.json 导航配置、现有教程目录结构
Storage: N/A
Testing: 文档构建与链接可达性检查（本地 docs 预览 + 静态路径校验）
Target Platform: VChart 官方文档站（zh 主路径，en 路径不新增正文）
Project Type: Rush Monorepo（文档子系统变更）
Performance Goals: 不引入额外运行时成本；页面加载复杂度与现有教程同级
Constraints: 必须与“快速上手”同级；教程内容与参考正文一致但需可验证；不得破坏现有导航结构
Scale/Scope: 1 篇新增教程 + 1 处导航配置调整 + 文档内链与示例片段

📝 Changelog

Language	Changelog
🇺🇸 English	Add a VChart Skill tutorial and place it at the same navigation level as Quick Start, with installation, editor references, and guided demo scenarios.
🇨🇳 Chinese

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

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🚀 Summary

copilot:summary

🔍 Walkthrough

copilot:walkthrough