Add an iPhone client sharing the macOS app's SwiftUI code

mac/Sources/Byre/ByreApp.swift

@@ -1,4 +1,3 @@
-import AppKit
 import SwiftUI
 
 #if DEBUG
@@ -7,6 +6,7 @@ import SwiftUI
 
 typealias ViewState = State
 
+#if os(macOS)
 @MainActor
 final class AppDelegate: NSObject, NSApplicationDelegate {
     private var quitting = false
@@ -132,3 +132,4 @@ struct ByreCommands: Commands {
         .disabled(focus?.store == nil || focus?.overlays.dialogOpen == true)
     }
 }
+#endif