Fix AddTextBox: add missing third arg (title) per API signature

Co-authored-by: Copilot <[email protected]>

Author: drewbatgit

hub/apps/develop/notifications/app-notifications/send-local-toast.md

@@ -262,7 +262,7 @@ var notification = new AppNotificationBuilder()
     ...
 
     // Text box for replying
-    .AddTextBox("tbReply", "Type a response")
+    .AddTextBox("tbReply", "Type a response", "Reply")
 
     // Buttons
     .AddButton(new AppNotificationButton("Reply")