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/answer.js

@@ -0,0 +1,9 @@
+const title = document.getElementById("title");
+const description = document.getElementById("description");
+const badge = document.getElementById("badge");
+
+title.textContent = "今天已完成 DOM 练习";
+description.textContent = "已经练习了元素选择、文本修改和样式切换。";
+description.style.color = "#2563eb";
+badge.textContent = "已完成";
+badge.classList.add("done");