feat: 实现大书远距目录跳转与后台补全优化方案

Phase 1: 稳定性优先
- 新增 RDEPUBJumpSession 保护机制，防止远距跳转后翻页串章
- 升级页图接管条件，增加 JumpSession 保护区检查
- 窗口扩展改为基于当前权威窗口方向

Phase 2: 补全优先级重排
- 新增 RDEPUBBackgroundPriorityPolicy 策略配置
- 实现 hot/warm/cold zone 优先级排序
- 添加失败重试机制（指数退避，最多3次）

Phase 3: 分段覆盖与最终收敛
- 新增 RDEPUBBackgroundCoverageStore 分段存储
- 新增 RDEPUBPageMapReconciliationCoordinator 页图接管仲裁
- 实现 LRU 淘汰和内存警告处理

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Sources/RDReaderView/EPUBUI/Settings/RDEPUBReaderConfiguration.swift

@@ -114,6 +114,11 @@ public struct RDEPUBReaderConfiguration: Equatable {
     /// 若 writeTotalMs 占比显著（I/O 等待），可试探 cpuCount * 1.25~1.5 以填充 I/O 等待间隙。
     public var metadataParsingConcurrency: Int
 
+    // MARK: JumpSession 策略
+
+    /// JumpSession 策略配置
+    public var jumpSessionPolicy: RDEPUBJumpSessionPolicy
+
     // MARK: 安全策略
 
     /// 允许直接打开的外部 URL scheme 集合，默认仅允许 https
@@ -172,6 +177,7 @@ public struct RDEPUBReaderConfiguration: Equatable {
         textRenderingEngine: RDEPUBTextRenderingEngine = .dtCoreText,
         onDemandChapterWindowSize: Int = 3,
         metadataParsingConcurrency: Int = ProcessInfo.processInfo.activeProcessorCount,
+        jumpSessionPolicy: RDEPUBJumpSessionPolicy = .default,
         allowedExternalURLSchemes: Set<String> = ["https"],
         requiresExternalLinkConfirmation: Bool = true,
         allowsInspectableWebViews: Bool = false,
@@ -197,6 +203,7 @@ public struct RDEPUBReaderConfiguration: Equatable {
         self.textRenderingEngine = textRenderingEngine
         self.onDemandChapterWindowSize = Self.normalizedChapterWindowSize(onDemandChapterWindowSize)
         self.metadataParsingConcurrency = max(1, metadataParsingConcurrency)
+        self.jumpSessionPolicy = jumpSessionPolicy
         self.allowedExternalURLSchemes = allowedExternalURLSchemes
         self.requiresExternalLinkConfirmation = requiresExternalLinkConfirmation
         self.allowsInspectableWebViews = allowsInspectableWebViews