feat: complete large-book pagination runtime and UI coverage

Sources/RDReaderView/ReaderView/RDReaderView+ContentAccess.swift

@@ -24,7 +24,7 @@ extension RDReaderView {
         }
         let contentViewClass = contentViews[identifier]
         assert(contentViewClass != nil, "请调用register(contentView：contentViewWithReuseIdentifier：）")
-        var contentView = contentViewClass!.init()
+        let contentView = contentViewClass!.init()
         return contentView
     }
 

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")