docs: add missing xml comments

src/AnthropicClient/Models/PingEventData.cs

@@ -1,7 +1,14 @@
 namespace AnthropicClient.Models;
 
+/// <summary>
+/// Represents data for a ping event.
+/// </summary>
 public class PingEventData : EventData
 {
+  /// <summary>
+  /// Initializes a new instance of the <see cref="PingEventData"/> class.
+  /// </summary>
+  /// <returns>A new instance of the <see cref="PingEventData"/> class.</returns>
   public PingEventData() : base(EventType.Ping)
   {
   }