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/11-input-live-preview/answer.js

@@ -0,0 +1,21 @@
+const nicknameInput = document.getElementById("nickname-input");
+const goalInput = document.getElementById("goal-input");
+const stageSelect = document.getElementById("stage-select");
+
+const previewStage = document.getElementById("preview-stage");
+const previewName = document.getElementById("preview-name");
+const previewGoal = document.getElementById("preview-goal");
+
+nicknameInput.addEventListener("input", function () {
+  const value = nicknameInput.value.trim();
+  previewName.textContent = value || "未填写昵称";
+});
+
+goalInput.addEventListener("input", function () {
+  const value = goalInput.value.trim();
+  previewGoal.textContent = value || "这里会显示你的学习目标。";
+});
+
+stageSelect.addEventListener("change", function () {
+  previewStage.textContent = stageSelect.value;
+});