feat: add TypeScript lessons and learning panel

- Introduced a new script to check TypeScript lesson files for errors.
- Created a main TypeScript file to render lessons and their details.
- Added lesson definitions with starter and answer codes.
- Implemented a user interface for navigating and running lessons.
- Styled the application with CSS for a better user experience.
- Updated README to reflect the new TypeScript section and usage instructions.

05-es6-plus/08-fetch-and-json/README.md

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+# 练习 8：fetch 和 JSON
+
+## 目标
+
+补齐 `fetch()` 和 `res.json()` 这一层最常见的现代异步写法。
+
+## 你要练什么
+
+- `fetch()`
+- `await`
+- `res.json()`
+- 接口数据渲染
+
+## 任务
+
+- 点击按钮后发起一次 `fetch`
+- 等待返回的响应对象
+- 调用 `res.json()` 解析 JSON
+- 把课程标题和内容渲染到页面
+
+## 文件
+
+- [starter.html](/Users/lijiaqing/home/wwwroot/front-end-example/05-es6-plus/08-fetch-and-json/starter.html)
+- [starter.js](/Users/lijiaqing/home/wwwroot/front-end-example/05-es6-plus/08-fetch-and-json/starter.js)
+- [answer.html](/Users/lijiaqing/home/wwwroot/front-end-example/05-es6-plus/08-fetch-and-json/answer.html)
+- [answer.js](/Users/lijiaqing/home/wwwroot/front-end-example/05-es6-plus/08-fetch-and-json/answer.js)