feat: 移除轮播图管理，系列活动改卡片布局，课程描述限10行，首页配置优化

backend/competition/urls.py

@@ -2,7 +2,7 @@ from django.urls import path, include
 from rest_framework.routers import DefaultRouter
 from .views import (
     CompetitionViewSet, ProjectViewSet, ProjectFileViewSet,
-    ScoreViewSet, CommentViewSet, CarouselItemViewSet, get_homepage_config
+    ScoreViewSet, CommentViewSet, get_homepage_config
 )
 from . import judge_views
 
@@ -12,7 +12,6 @@ router.register(r'projects', ProjectViewSet, basename='project')
 router.register(r'files', ProjectFileViewSet, basename='projectfile')
 router.register(r'scores', ScoreViewSet, basename='score')
 router.register(r'comments', CommentViewSet, basename='comment')
-router.register(r'carousel-items', CarouselItemViewSet, basename='carouselitem')
 
 urlpatterns = [
     # 首页配置