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.

04-dom-events-async/12-prepend-remove-and-link-default/starter.js

@@ -0,0 +1,6 @@
+// 任务：
+// 1. 获取两个按钮、帮助链接、提示文字和列表
+// 2. 点击 prepend-btn 时创建新 li，并插入到列表最前面
+// 3. 点击 clear-active-btn 时移除所有 item 的 active 类名
+// 4. 点击帮助链接时，用 preventDefault() 阻止跳转
+// 5. 在提示文字里输出“已阻止默认跳转”