feat: 更新考试相关页面，添加刷新功能，修改考试状态显示

- 注：当前代码还存在bug：查看结果暂出现错误。
- 在 SubjectSelectionPage 页面中添加刷新按钮，允许用户手动刷新考试任务列表。
- 修改 UserTaskPage 页面，重构考试任务为答题记录，更新数据结构和状态显示。
- 在 AdminDashboardPage、UserManagePage、UserRecordsPage 等管理页面中添加考试状态显示，使用不同颜色区分状态（不及格、合格、优秀）。
- 在 ResultPage 中显示考试状态，确保用户能够清晰了解考试结果。
- 添加约束，确保单次考试试卷中题目不可重复出现，并记录相关规范。
- 添加评分状态约束，根据得分占比自动计算考试状态，并在结果页面显示。

api/models/quiz.ts

@@ -8,7 +8,13 @@ export interface QuizRecord {
   totalScore: number;
   correctCount: number;
   totalCount: number;
+  scorePercentage: number;
+  status: '不及格' | '合格' | '优秀';
   createdAt: string;
+  subjectId?: string;
+  subjectName?: string;
+  taskId?: string;
+  taskName?: string;
 }
 
 export interface QuizAnswer {
@@ -39,15 +45,25 @@ export interface SubmitQuizData {
 }
 
 export class QuizModel {
+  // 计算考试状态
+  private static calculateStatus(scorePercentage: number): '不及格' | '合格' | '优秀' {
+    if (scorePercentage < 60) return '不及格';
+    if (scorePercentage < 80) return '合格';
+    return '优秀';
+  }
+
   // 创建答题记录
   static async createRecord(data: { userId: string; totalScore: number; correctCount: number; totalCount: number }): Promise<QuizRecord> {
     const id = uuidv4();
+    const scorePercentage = data.totalCount > 0 ? (data.totalScore / data.totalCount) * 100 : 0;
+    const status = this.calculateStatus(scorePercentage);
+    
     const sql = `
-      INSERT INTO quiz_records (id, user_id, total_score, correct_count, total_count) 
-      VALUES (?, ?, ?, ?, ?)
+      INSERT INTO quiz_records (id, user_id, total_score, correct_count, total_count, score_percentage, status) 
+      VALUES (?, ?, ?, ?, ?, ?, ?)
     `;
     
-    await run(sql, [id, data.userId, data.totalScore, data.correctCount, data.totalCount]);
+    await run(sql, [id, data.userId, data.totalScore, data.correctCount, data.totalCount, scorePercentage, status]);
     return this.findRecordById(id) as Promise<QuizRecord>;
   }
 
@@ -114,7 +130,7 @@ export class QuizModel {
 
   // 根据ID查找答题记录
   static async findRecordById(id: string): Promise<QuizRecord | null> {
-    const sql = `SELECT id, user_id as userId, total_score as totalScore, correct_count as correctCount, total_count as totalCount, created_at as createdAt FROM quiz_records WHERE id = ?`;
+    const sql = `SELECT id, user_id as userId, total_score as totalScore, correct_count as correctCount, total_count as totalCount, score_percentage as scorePercentage, status, created_at as createdAt FROM quiz_records WHERE id = ?`;
     const record = await get(sql, [id]);
     return record || null;
   }
@@ -122,10 +138,15 @@ export class QuizModel {
   // 获取用户的答题记录
   static async findRecordsByUserId(userId: string, limit = 10, offset = 0): Promise<{ records: QuizRecord[]; total: number }> {
     const recordsSql = `
-      SELECT id, user_id as userId, total_score as totalScore, correct_count as correctCount, total_count as totalCount, created_at as createdAt 
-      FROM quiz_records 
-      WHERE user_id = ? 
-      ORDER BY created_at DESC 
+      SELECT r.id, r.user_id as userId, r.total_score as totalScore, r.correct_count as correctCount, r.total_count as totalCount, 
+             r.score_percentage as scorePercentage, r.status, r.created_at as createdAt,
+             r.subject_id as subjectId, s.name as subjectName,
+             r.task_id as taskId, t.name as taskName
+      FROM quiz_records r 
+      LEFT JOIN exam_subjects s ON r.subject_id = s.id
+      LEFT JOIN exam_tasks t ON r.task_id = t.id
+      WHERE r.user_id = ? 
+      ORDER BY r.created_at DESC 
       LIMIT ? OFFSET ?
     `;
     
@@ -147,6 +168,7 @@ export class QuizModel {
     const recordsSql = `
       SELECT r.id, r.user_id as userId, u.name as userName, u.phone as userPhone, 
              r.total_score as totalScore, r.correct_count as correctCount, r.total_count as totalCount, 
+             r.score_percentage as scorePercentage, r.status,
              r.created_at as createdAt, r.subject_id as subjectId, s.name as subjectName,
              r.task_id as taskId
       FROM quiz_records r