feat: EPUB阅读器搜索、注释、CFI模块及大书远距跳转优化

- 实现EPUB阅读器搜索功能及选中注释功能
- 优化CFI模块，修复代码审查发现的11个问题
- 实现大书远距目录跳转与后台补全优化方案
- 优化设置面板与章节运行时联动
- 重构及大量改进优化

Sources/RDReaderView/EPUBCore/CFI/RDEPUBCFIDOMPathBuilder.swift

@@ -75,7 +75,7 @@ public enum RDEPUBCFIDOMPathBuilder {
               match.numberOfRanges > 2 else {
             return nil
         }
-        return nsAttributes.substring(with: match.range(at: 2)).nilIfEmpty
+        return nsAttributes.substring(with: match.range(at: 2)).rd_cfiNilIfEmpty
     }
 
     static func isIgnorableTag(_ tagName: String) -> Bool {
@@ -162,7 +162,7 @@ enum RDEPUBCFITextNodeMapBuilder {
         }
 
         // Use comment/CDATA-stripped HTML for both path building and tag matching
-        let cleanedHTML = stripCommentsAndCDATA(rawHTML)
+        let cleanedHTML = RDEPUBCFIDOMPathBuilder.stripCommentsAndCDATA(rawHTML)
 
         let fragments = RDEPUBCFIDOMPathBuilder.fragmentPaths(in: rawHTML)
         var markers: [RDEPUBCFIMarker] = fragmentMarkers(fragmentOffsets: fragmentOffsets, paths: fragments)
@@ -516,6 +516,14 @@ private struct RDEPUBNormalizedTextIndex {
     }
 }
 
+extension String {
+    var rd_cfiNilIfEmpty: String? {
+        let trimmed = trimmingCharacters(in: .whitespacesAndNewlines)
+        return trimmed.isEmpty ? nil : trimmed
+    }
+
+}
+
 private extension String {
     var fnv1a64: UInt64 {
         let offsetBasis: UInt64 = 14695981039346656037