enter intro cutscene

SdkServer/Utils/JsonStringToObjectConverter.cs

@@ -0,0 +1,24 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace MikuSB.SdkServer.Utils;
+
+public class JsonStringToObjectConverter<T> : JsonConverter<T> where T : class
+{
+    public override T? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.TokenType != JsonTokenType.String)
+            return JsonSerializer.Deserialize<T>(ref reader, options);
+
+        var jsonString = reader.GetString();
+        return !string.IsNullOrEmpty(jsonString)
+            ? JsonSerializer.Deserialize<T>(jsonString, options)
+            : null;
+    }
+
+    public override void Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
+    {
+        var json = JsonSerializer.Serialize(value, options);
+        writer.WriteStringValue(json);
+    }
+}