修复判断题答案图标显示问题

- 当判断题答案为"错误"时，显示叉号图标(CloseCircleOutlined)而非对号
- 当判断题答案为"正确"时，保持显示对号图标(CheckCircleOutlined)
- 优化视觉反馈，使答案图标更加直观明确

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

web/src/pages/QuestionList.tsx

@@ -17,6 +17,7 @@ import {
 import {
   BookOutlined,
   CheckCircleOutlined,
+  CloseCircleOutlined,
   EditOutlined,
   FileTextOutlined,
   UnorderedListOutlined,
@@ -316,7 +317,7 @@ const QuestionList: React.FC = () => {
                         color={question.answer === true ? 'success' : 'error'}
                         className={styles.trueFalseTag}
                       >
-                        <CheckCircleOutlined /> {question.answer === true ? '正确' : '错误'}
+                        {question.answer === true ? <CheckCircleOutlined /> : <CloseCircleOutlined />} {question.answer === true ? '正确' : '错误'}
                       </Tag>
                     </div>
                   )}