fix(notification): harden local alerts

ios/Runner/AppDelegate.swift

@@ -1,5 +1,6 @@
 import Flutter
 import UIKit
+import UserNotifications
 
 @main
 @objc class AppDelegate: FlutterAppDelegate {
@@ -7,7 +8,16 @@ import UIKit
     _ application: UIApplication,
     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
   ) -> Bool {
+    UNUserNotificationCenter.current().delegate = self
     GeneratedPluginRegistrant.register(with: self)
     return super.application(application, didFinishLaunchingWithOptions: launchOptions)
   }
+
+  func userNotificationCenter(
+    _ center: UNUserNotificationCenter,
+    willPresent notification: UNNotification,
+    withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void
+  ) {
+    completionHandler([.banner, .sound, .badge])
+  }
 }