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/EPUBCore/RDEPUBSafeArea.swift

@@ -0,0 +1,67 @@
+import UIKit
+
+/// Device-level safe area lookup modeled after GKNavigationBarSwift.
+/// Reads the real safe area from the key window so correct values are
+/// available even before a view has been laid out in the hierarchy.
+/// Must be called on the main thread.
+public enum RDEPUBSafeArea {
+
+    /// Minimum text margins applied when the device safe area on an edge is
+    /// smaller (e.g. no notch / no home indicator). These are aesthetic
+    /// paddings, not approximations of the safe area itself.
+    public static let minimumVerticalTextMargin: CGFloat = 20
+
+    public static let minimumHorizontalTextMargin: CGFloat = 16
+
+    public static func keyWindow() -> UIWindow? {
+        let scenes = UIApplication.shared.connectedScenes
+            .compactMap { $0 as? UIWindowScene }
+        if let window = scenes
+            .filter({ $0.activationState == .foregroundActive })
+            .flatMap({ $0.windows })
+            .first(where: { $0.isKeyWindow }) {
+            return window
+        }
+        if let window = scenes
+            .flatMap({ $0.windows })
+            .first(where: { $0.isKeyWindow }) {
+            return window
+        }
+        return UIApplication.shared.delegate?.window ?? nil
+    }
+
+    public static func insets() -> UIEdgeInsets {
+        if let window = keyWindow() {
+            return window.safeAreaInsets
+        }
+        // No key window yet (early launch): create a detached window to read
+        // the device safe area, same fallback as GKNavigationBarSwift.
+        let window = UIWindow(frame: UIScreen.main.bounds)
+        if window.safeAreaInsets.bottom <= 0 {
+            window.rootViewController = UIViewController()
+        }
+        return window.safeAreaInsets
+    }
+
+    /// Prefers insets measured from a view already installed in the hierarchy;
+    /// falls back to the key-window insets when the view is not laid out yet
+    /// and reports .zero.
+    public static func resolve(_ measuredInsets: UIEdgeInsets?) -> UIEdgeInsets {
+        if let measuredInsets, measuredInsets != .zero {
+            return measuredInsets
+        }
+        return insets()
+    }
+
+    /// Default reflowable content insets derived from the live device safe
+    /// area instead of hard-coded heights.
+    public static func defaultReflowableContentInsets() -> UIEdgeInsets {
+        let safe = insets()
+        return UIEdgeInsets(
+            top: max(safe.top, minimumVerticalTextMargin),
+            left: max(safe.left, minimumHorizontalTextMargin),
+            bottom: max(safe.bottom, minimumVerticalTextMargin),
+            right: max(safe.right, minimumHorizontalTextMargin)
+        )
+    }
+}