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/02-text-class-style/starter.js

@@ -0,0 +1,5 @@
+// 任务：
+// 1. 选中标题、描述、状态标签
+// 2. 修改标题文字
+// 3. 给标签加上 done 类名
+// 4. 修改描述文字颜色