refactor: chat input

ios/Runner/AppDelegate.swift

@@ -145,24 +145,16 @@ class BackgroundStreamingHandler: NSObject {
   ) -> Bool {
     GeneratedPluginRegistrant.register(with: self)
     
-    // Setup background streaming handler with scene-safe rootViewController access
-    var controller: FlutterViewController?
-    if let scene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
-       let root = scene.windows.first?.rootViewController as? FlutterViewController {
-      controller = root
-    } else if let legacy = window?.rootViewController as? FlutterViewController {
-      controller = legacy
-    }
-
-    if let controller {
+    // Setup background streaming handler using the plugin registry messenger
+    if let registrar = self.registrar(forPlugin: "BackgroundStreamingHandler") {
       let channel = FlutterMethodChannel(
         name: "conduit/background_streaming",
-        binaryMessenger: controller.binaryMessenger
+        binaryMessenger: registrar.messenger()
       )
-      
+
       backgroundStreamingHandler = BackgroundStreamingHandler()
       backgroundStreamingHandler?.setup(with: channel)
-      
+
       // Register method call handler
       channel.setMethodCallHandler { [weak self] (call, result) in
         self?.backgroundStreamingHandler?.handle(call, result: result)