feat(epub): complete wxread parity scope

Sources/RDReaderView/EPUBCore/RDEPUBRenderRequest.swift

@@ -41,6 +41,10 @@ public struct RDEPUBPresentationStyle: Equatable {
     public var fontSize: CGFloat
     /// 行距倍数（1.0 为默认行距）
     public var lineHeightMultiple: CGFloat
+    /// 栏数，对标 WXRead 的多栏分页配置
+    public var numberOfColumns: Int
+    /// 栏间距，对标 WXRead 的 columnGap
+    public var columnGap: CGFloat
     /// 主题背景色（CSS 颜色值，如 "#FFFFFF"）
     public var themeBackgroundColor: String?
     /// 主题文字色（CSS 颜色值，如 "#000000"）
@@ -51,6 +55,8 @@ public struct RDEPUBPresentationStyle: Equatable {
         contentInsets: UIEdgeInsets,
         fontSize: CGFloat,
         lineHeightMultiple: CGFloat,
+        numberOfColumns: Int = 1,
+        columnGap: CGFloat = 20,
         themeBackgroundColor: String? = nil,
         themeTextColor: String? = nil
     ) {
@@ -58,6 +64,8 @@ public struct RDEPUBPresentationStyle: Equatable {
         self.contentInsets = contentInsets
         self.fontSize = fontSize
         self.lineHeightMultiple = lineHeightMultiple
+        self.numberOfColumns = max(1, numberOfColumns)
+        self.columnGap = max(0, columnGap)
         self.themeBackgroundColor = themeBackgroundColor
         self.themeTextColor = themeTextColor
     }
@@ -170,4 +178,4 @@ public enum RDEPUBRenderRequest: Equatable {
             return request.spread.primaryResource.href
         }
     }
-}
+}