feat: add type for ephemeral cache control

src/AnthropicClient/Models/EphemeralCacheControl.cs

@@ -0,0 +1,13 @@
+namespace AnthropicClient.Models;
+
+/// <summary>
+/// Represents the cache control to be used for content.
+/// </summary>
+public class EphemeralCacheControl : CacheControl
+{
+  /// <summary>
+  /// Initializes a new instance of the <see cref="EphemeralCacheControl"/> class.
+  /// </summary>
+  /// <returns>A new instance of the <see cref="EphemeralCacheControl"/> class.</returns>
+  public EphemeralCacheControl() : base(CacheControlType.Ephemeral) { }
+}