feat(epub): align wxread css and overlay pagination behavior

Sources/RDReaderView/EPUBTextRendering/RDEPUBTextBookBuilder.swift

@@ -177,6 +177,7 @@ public struct RDEPUBTextBook {
 public final class RDEPUBTextBookBuilder {
     private let renderer: RDEPUBTextRenderer
     private let cache: RDEPUBTextBookCache?
+    private let layoutConfig: RDEPUBTextLayoutConfig
     private let sampler: RDEPUBTextPerformanceSampler
 
     /// 最后一次构建的资源引用诊断（样式表、图片等）
@@ -188,9 +189,14 @@ public final class RDEPUBTextBookBuilder {
     /// 最后一次构建的缓存命中/未命中统计
     public private(set) var lastBuildCacheStats: (hits: Int, misses: Int) = (0, 0)
 
-    public init(renderer: RDEPUBTextRenderer, cache: RDEPUBTextBookCache? = nil) {
+    public init(
+        renderer: RDEPUBTextRenderer,
+        cache: RDEPUBTextBookCache? = nil,
+        layoutConfig: RDEPUBTextLayoutConfig = .default
+    ) {
         self.renderer = renderer
         self.cache = cache
+        self.layoutConfig = layoutConfig
         self.sampler = RDEPUBTextPerformanceSampler()
     }
 
@@ -268,7 +274,8 @@ public final class RDEPUBTextBookBuilder {
                 rawHTML: rawHTML,
                 baseURL: parser.fileURL(forRelativePath: item.href)?.deletingLastPathComponent(),
                 style: style,
-                resourceResolver: publication.resourceResolver
+                resourceResolver: publication.resourceResolver,
+                contentLanguageCode: publication.metadata.language
             )
 
             // 渲染 HTML → NSAttributedString
@@ -339,7 +346,7 @@ public final class RDEPUBTextBookBuilder {
             } else {
                 // 缓存未命中：调用 CoreText 分页引擎
                 layoutFrames = content.length > 0
-                    ? content.rd_paginatedFrames(size: pageSize, fragmentOffsets: rendered.fragmentOffsets)
+                    ? content.rd_paginatedFrames(size: pageSize, fragmentOffsets: rendered.fragmentOffsets, config: layoutConfig)
                     : []
                 isCacheHit = false
             }
@@ -711,7 +718,8 @@ public final class RDEPUBTextBookBuilder {
             fontSize: style.font.pointSize,
             lineHeightMultiple: style.lineSpacing,
             contentInsets: .zero,
-            pageSize: pageSize
+            pageSize: pageSize,
+            layoutConfigSignature: layoutConfig.cacheSignature
         )
     }
 }