feat(my): add 我的考试 page and related modules

1. 新增我的考试页面，包含学科筛选Tab和分页考试列表
2. 新增学科图标工具类，替换我的报告页重复的学科图标逻辑
3. 在我的页面菜单中添加我的考试入口
4. 新增exam模块的API接口和数据模型
5. 优化我的报告页面卡片样式，统一与考试卡片的布局

lib/core/router/app_router.dart

@@ -17,6 +17,7 @@ import 'package:new_learn/features/conquerPackage/captureList/index.dart';
 import 'package:new_learn/features/my/my_point/my_point_page.dart';
 import 'package:new_learn/features/my/my_report/my_report_page.dart';
 import 'package:new_learn/features/my/my_report/report_detail_page.dart';
+import 'package:new_learn/features/my/exam/exam_page.dart';
 import 'package:new_learn/features/my/settings/settings_page.dart';
 import 'package:new_learn/features/my/settings/about_app_page.dart';
 import 'package:new_learn/features/recite/recite_page.dart';
@@ -138,6 +139,7 @@ final GoRouter appRouter = GoRouter(
     ),
     GoRoute(path: '/myPoint', builder: (_, _) => const MyPointPage()),
     GoRoute(path: '/myReport', builder: (_, _) => const MyReportPage()),
+    GoRoute(path: '/myExam', builder: (_, _) => const ExamPage()),
     GoRoute(
       path: '/report-detail',
       builder: (_, state) {
@@ -185,8 +187,7 @@ final GoRouter appRouter = GoRouter(
     // ---------- 攻克包 - 截图名单 ----------
     GoRoute(
       path: '/conquerPackage/captureList',
-      builder: (_, state) =>
-          CaptureListPage(courseId: state.extra as String),
+      builder: (_, state) => CaptureListPage(courseId: state.extra as String),
     ),
     GoRoute(path: '/register', builder: (_, _) => const RegisterPage()),