feat: create chat message

src/AnthropicClient/Json/JsonSerializationOptions.cs

@@ -0,0 +1,20 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace AnthropicClient.Json;
+
+static class JsonSerializationOptions
+{
+  public static JsonSerializerOptions DefaultOptions => new()
+  {
+    PropertyNameCaseInsensitive = true,
+    PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+    Converters =
+    {
+      new ContentConverter(),
+      new ToolChoiceConverter(),
+      new ErrorConverter(),
+    },
+    DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
+  };
+}