feat: 新增过渡页面路由、上传组件及完善跳转逻辑

- 为conquerPackage模块添加过渡页面路由并实现页面跳转逻辑
- 新增通用多图上传组件Upload，支持多种模式与图片操作功能
- 新增任务相关的API及Model基础文件
- 注释课前课中页面的测试试题内容

lib/core/router/app_router.dart

@@ -16,6 +16,7 @@ import 'package:new_learn/features/my/my_page.dart';
 import 'package:new_learn/features/my/note/note_page.dart';
 import 'package:new_learn/features/conquerPackage/captureList/index.dart';
 import 'package:new_learn/features/conquerPackage/beforeDuringClass/index.dart';
+import 'package:new_learn/features/conquerPackage/transitionPage/transition_page.dart';
 import 'package:new_learn/features/my/my_point/my_point_page.dart';
 import 'package:new_learn/features/my/question_list/question_list_page.dart';
 import 'package:new_learn/features/my/my_report/my_report_page.dart';
@@ -210,6 +211,12 @@ final GoRouter appRouter = GoRouter(
         extra: state.extra as Map<String, dynamic>?,
       ),
     ),
+    GoRoute(
+      path: '/conquerPackage/transitionPage',
+      builder: (_, state) => TransitionPage(
+        extra: state.extra as Map<String, dynamic>?,
+      ),
+    ),
     GoRoute(path: '/register', builder: (_, _) => const RegisterPage()),
 
     // app_router.dart 的 routes 里加，不用管跳转逻辑