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

mac/Sources/Byre/EventStream.swift

@@ -1,6 +1,6 @@
-import AppKit
 import Foundation
 import Network
+import SwiftUI
 
 private let staleAfter: TimeInterval = 40
 private let retryAfter: Duration = .seconds(2)
@@ -50,9 +50,15 @@ final class EventStream {
             }
         }
         monitor.start(queue: .main)
+        #if os(macOS)
         activeObserver = NotificationCenter.default.addObserver(of: NSApplication.self, for: .didBecomeActive) { [weak self] _ in
             self?.check()
         }
+        #else
+        activeObserver = NotificationCenter.default.addObserver(of: UIApplication.self, for: .didBecomeActive) { [weak self] _ in
+            self?.check()
+        }
+        #endif
         connect()
     }