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/07-arrow-this/starter.js

@@ -0,0 +1,11 @@
+const trainer = {
+  name: "现代 JS 训练营",
+  report() {
+    // 任务：
+    // 1. 用 setTimeout
+    // 2. 在回调里用箭头函数读取 this.name
+    // 3. 把结果写入 #output
+  },
+};
+
+trainer.report();