refactor: rename RDReaderView -> RDEpubReaderView, update pod config and docs

- Rename source module from RDReaderView to RDEpubReaderView
- Move all source files from Sources/RDReaderView/ to Sources/RDEpubReaderView/
- Update podspec: RDReaderView.podspec -> RDEpubReaderView.podspec
- Update Podfile, demo project, and CocoaPods config for new pod name
- Delete old RDReaderView pod support files from ReadViewDemo/Pods
- Add new RDEpubReaderView pod support files
- Update documentation (API ref, architecture, UML, conventions, etc.)
- Add FixedLayoutRotationTests
- Update .gitignore: exclude .DS_Store, manual unpack backups, _ssoft-output

Sources/RDEpubReaderView/EPUBUI/RDEPUBReaderController+Orientation.swift

@@ -0,0 +1,48 @@
+import UIKit
+
+/// 朝向锁定支持。
+///
+/// 依据 `publication.metadata.orientation`（来源 OPF rendition:orientation，
+/// 或兜底的 iBooks display-options）返回受限的支持朝向，并在书籍打开后主动请求转向。
+/// 未声明朝向（nil / .auto）时不干预，跟随系统与容器。
+///
+/// 注意：`supportedInterfaceOrientations` 只有当阅读器是当前决定朝向的控制器时才生效
+/// （通常需宿主保证它被 present 或位于导航栈顶；若被包在自定义容器里，容器需转发该值）。
+extension RDEPUBReaderController {
+
+    /// 由 EPUB 元数据推导的受限支持朝向；nil = 不限制（跟随系统）
+    var epubSupportedOrientationMask: UIInterfaceOrientationMask? {
+        switch publication?.metadata.orientation {
+        case .portrait:
+            return .portrait
+        case .landscape:
+            return .landscape
+        case .auto, .none:
+            return nil
+        }
+    }
+
+    public override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
+        epubSupportedOrientationMask ?? super.supportedInterfaceOrientations
+    }
+
+    public override var shouldAutorotate: Bool {
+        // 已锁定单一朝向时不自动旋转
+        epubSupportedOrientationMask == nil
+    }
+
+    /// 打开书籍后按元数据主动转向（iOS 16+ 用 requestGeometryUpdate，旧系统回退到刷新支持朝向）。
+    /// 由加载完成流程调用。
+    func applyOrientationLockIfNeeded() {
+        guard let mask = epubSupportedOrientationMask else { return }
+        if #available(iOS 16.0, *) {
+            setNeedsUpdateOfSupportedInterfaceOrientations()
+            guard let scene = view.window?.windowScene else { return }
+            scene.requestGeometryUpdate(.iOS(interfaceOrientations: mask)) { _ in }
+        } else {
+            let target: UIInterfaceOrientation = (mask == .landscape) ? .landscapeRight : .portrait
+            UIDevice.current.setValue(target.rawValue, forKey: "orientation")
+            UIViewController.attemptRotationToDeviceOrientation()
+        }
+    }
+}