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>

ReadViewDemo/ReadViewDemoUITests/ReaderUITests/AsyncChapterLoadingTests.swift

@@ -17,6 +17,7 @@ final class AsyncChapterLoadingTests: XCTestCase {
 
     private let app = XCUIApplication()
     private let largeBook = "凡人修仙传"
+    private let singlePageOpeningBook = "宝山辽墓"
 
     override func setUpWithError() throws {
         continueAfterFailure = false
@@ -106,6 +107,25 @@ final class AsyncChapterLoadingTests: XCTestCase {
 
     // MARK: - 3. Cross-chapter page turning in scroll mode
 
+    func testSinglePageOpeningChapterIncludesImmediateLookaheadPages() throws {
+        app.launchAndOpenSampleBook(
+            bookTitleQuery: singlePageOpeningBook,
+            displayType: "scroll",
+            resetsReaderState: true
+        )
+        app.waitForReader(timeout: 20)
+
+        let initialState = app.waitForDemoReaderState(timeout: 15, description: "首开局部分页可立即前翻") { state in
+            state.mode == "bookPageMap" && state.knownPages != nil
+        }
+
+        XCTAssertGreaterThan(
+            initialState.knownPages ?? 0,
+            1,
+            "首章只有 1 页时，首开局部分页也应补充前瞻页，避免停留在总页数=1"
+        )
+    }
+
     func testCrossChapterPageTurningInScrollMode() throws {
         // Swipes forward across a chapter boundary in horizontal scroll mode,
         // verifying continuous page number increments.