feat: complete large-book pagination runtime and UI coverage

Sources/RDReaderView/ReaderView/RDReaderView.swift

@@ -742,6 +742,13 @@ public class RDReaderView: UIView {
         bottomToolView = resolvedBottomChromeView()
     }
 
+    /// 仅刷新总页数，不重建页面内容（用于后台元数据解析期间避免刷新掉用户选区）
+    public func reloadPageCountOnly() {
+        collectionView.reloadData()
+        topToolView = resolvedTopChromeView()
+        bottomToolView = resolvedBottomChromeView()
+    }
+
 
     required init?(coder: NSCoder) {
         fatalError("init(coder:) has not been implemented")