feat: 交互协调器拆分、附件提示、暗色图片适配、选区放大镜及文档清理

- 拆分 ContentDelegates/TextContentView 为独立协调器（InteractionCoordinator、LocationResolution、ExternalLinks、AttachmentTooltip）
- 新增 RDEPUBAttachmentTooltipView/OverlayView 附件气泡提示
- 新增 RDEPUBDarkImageAdjuster 暗色模式图片亮度适配
- 新增 RDEPUBSelectionLoupeView 选区放大镜
- 新增 MetadataParseWorker/CancellationController 元数据解析取消机制
- 重构 PresentationRuntime/PaginationCoordinator 精简职责
- 优化 ChapterLoader/WarmupOrchestrator 异步章节加载
- CFI 模块微调与 NoteModels 更新
- 清理冗余文档，更新架构/UML/业务逻辑文档

Co-Authored-By: Claude <noreply@anthropic.com>

Sources/RDReaderView/EPUBUI/RDEPUBReaderSearchBarView.swift

@@ -99,7 +99,7 @@ final class RDEPUBReaderSearchBarView: RDEPUBReaderToolView {
 
     override func apply(theme: RDEPUBReaderTheme) {
         super.apply(theme: theme)
-        let isDarkBackground = theme.contentBackgroundColor.rd_searchIsDarkBackground
+        let isDarkBackground = theme.contentBackgroundColor.rd_isDarkBackground
 
         let overlayColor = isDarkBackground
             ? UIColor(white: 0.12, alpha: 0.92)
@@ -422,21 +422,6 @@ final class RDEPUBReaderSearchBarView: RDEPUBReaderToolView {
     }
 }
 
-private extension UIColor {
-
-    var rd_searchIsDarkBackground: Bool {
-        var red: CGFloat = 0
-        var green: CGFloat = 0
-        var blue: CGFloat = 0
-        var alpha: CGFloat = 0
-        guard getRed(&red, green: &green, blue: &blue, alpha: &alpha) else {
-            return false
-        }
-        let luminance = (0.299 * red) + (0.587 * green) + (0.114 * blue)
-        return luminance < 0.5
-    }
-}
-
 extension RDEPUBReaderSearchBarView: UITableViewDataSource, UITableViewDelegate {
 
     func numberOfSections(in tableView: UITableView) -> Int {