feat: implement GetMessageBatchResultsAsync method

src/AnthropicClient/Models/CanceledMessageBatchResult.cs

@@ -0,0 +1,14 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents a message batch result that was cancelled.
+/// </summary>
+public class CanceledMessageBatchResult : MessageBatchResult
+{
+  /// <summary>
+  /// Initializes a new instance of the <see cref="CanceledMessageBatchResult"/> class.
+  /// </summary>
+  public CanceledMessageBatchResult() : base(MessageBatchResultType.Canceled)
+  {
+  }
+}