feat: 添加双人对练功能

- 新增数据库迁移脚本 (practice_rooms, practice_room_messages)
- 新增后端 API: 房间创建/加入/消息同步/报告生成
- 新增前端页面: 入口页/对练房间/报告页
- 新增 AI 双人评估服务和提示词

backend/app/api/v1/__init__.py

@@ -29,6 +29,7 @@ from .sql_executor import router as sql_executor_router
 
 from .exam import router as exam_router
 from .practice import router as practice_router
+from .practice_room import router as practice_room_router
 from .course_chat import router as course_chat_router
 from .broadcast import router as broadcast_router
 from .preview import router as preview_router
@@ -69,6 +70,8 @@ api_router.include_router(sql_executor_router, prefix="/sql", tags=["sql-executo
 api_router.include_router(exam_router, tags=["exams"])
 # practice_router 陪练功能路由
 api_router.include_router(practice_router, prefix="/practice", tags=["practice"])
+# practice_room_router 双人对练房间路由（prefix在router内部定义为/practice/rooms）
+api_router.include_router(practice_room_router, tags=["practice-room"])
 # course_chat_router 与课程对话路由
 api_router.include_router(course_chat_router, prefix="/course", tags=["course-chat"])
 # broadcast_router 播课功能路由（不添加prefix，路径在router内部定义）