feat: follow llm.txt

backend/pkg/consts/consts.go

@@ -77,6 +77,12 @@ type ContentVisibility string
 // ENUM( main, cover, preview )
 type ContentAssetRole string
 
+const (
+	// DefaultContentPreviewSeconds is the default preview duration in seconds when content.preview_seconds is unset/invalid.
+	// 默认试看时长（秒）：当未配置或传入非法值时使用。
+	DefaultContentPreviewSeconds int32 = 60
+)
+
 // content_prices
 
 // swagger:enum DiscountType