feat(apple): native SwiftUI app for iOS and macOS

Add a native SwiftUI VniDrop app (Send/Receive/Settings) talking to the
Rust core via generated UniFFI Swift bindings, plus the uniffi-bindgen
helper crate. iOS uses a TabView, macOS a NavigationSplitView sidebar.

apple/VniDrop/UI/Components/PlatformImage.swift

@@ -0,0 +1,20 @@
+import SwiftUI
+
+/// Cross-platform decoding of raw image bytes into a SwiftUI `Image`.
+enum PlatformImage {
+	static func from(data: Data) -> Image? {
+		#if os(iOS)
+		guard let ui = UIImage(data: data) else { return nil }
+		return Image(uiImage: ui)
+		#else
+		guard let ns = NSImage(data: data) else { return nil }
+		return Image(nsImage: ns)
+		#endif
+	}
+}
+
+#if os(iOS)
+import UIKit
+#else
+import AppKit
+#endif