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/EPUBCore/Notes/RDEPUBNoteModels.swift

@@ -41,7 +41,7 @@ public struct RDEPUBNoteReference: Codable, Equatable {
         self.targetHref = targetHref
         self.targetFragment = targetFragment
         self.targetCFI = targetCFI
-        self.label = label?.rdNoteNilIfEmpty
+        self.label = label?.rd_nilIfEmpty
         self.kind = kind
     }
 }
@@ -71,15 +71,8 @@ public struct RDEPUBResolvedNote: Equatable {
         self.reference = reference
         self.sourceLocation = sourceLocation
         self.targetLocation = targetLocation
-        self.title = title?.rdNoteNilIfEmpty
+        self.title = title?.rd_nilIfEmpty
         self.html = html
         self.plainText = plainText
     }
 }
-
-private extension String {
-    var rdNoteNilIfEmpty: String? {
-        let trimmed = trimmingCharacters(in: .whitespacesAndNewlines)
-        return trimmed.isEmpty ? nil : trimmed
-    }
-}