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/ReaderView/Paging/RDEpubReaderPagingController.swift

@@ -0,0 +1,45 @@
+import UIKit
+
+struct RDEpubReaderPagingController {
+
+    struct PageTransitionRequest: Equatable {
+        let pageNum: Int
+        let animated: Bool
+    }
+
+    var pendingTransitionRequest: PageTransitionRequest?
+
+    var isTransitioning: Bool = false
+
+    var didBuildUI = false
+
+    static func createPageViewController(isDualPage: Bool) -> UIPageViewController {
+        let options: [UIPageViewController.OptionsKey: Any]?
+        if isDualPage {
+            options = [.spineLocation: NSNumber(value: UIPageViewController.SpineLocation.mid.rawValue)]
+        } else {
+            options = nil
+        }
+        let pageVC = UIPageViewController(transitionStyle: .pageCurl, navigationOrientation: .horizontal, options: options)
+        pageVC.isDoubleSided = isDualPage
+        return pageVC
+    }
+
+    mutating func shouldQueuePageTransition(_ request: PageTransitionRequest, currentDisplayType: RDEpubReaderView.DisplayType) -> Bool {
+        guard currentDisplayType == .pageCurl, isTransitioning else { return false }
+        pendingTransitionRequest = request
+        return true
+    }
+
+    mutating func finishPageCurlTransition() -> PageTransitionRequest? {
+        isTransitioning = false
+        guard let pending = pendingTransitionRequest else { return nil }
+        pendingTransitionRequest = nil
+        return pending
+    }
+
+    mutating func resetPendingState() {
+        isTransitioning = false
+        pendingTransitionRequest = nil
+    }
+}