feat: 代码片段功能与 Markdown 内嵌片段渲染、文档截图等

backend/handler/handlers.go

@@ -42,6 +42,7 @@ type Handlers struct {
 	Badge          *service.BadgeService
 	LeaderboardSvc *service.LeaderboardService
 	LibrarySvc     *service.LibraryService
+	SnippetSvc     *service.SnippetService
 }
 
 // resolvePublishStatus 决定新帖/新评的初始状态：