fix: support Visual Studio 2026 package loading

visualstudio-extension/Prophet.CoopWithDsh/SnapshotPublisher.cs

@@ -1,12 +1,13 @@
 using System;
 using System.IO;
+using System.Runtime.Serialization.Json;
 using System.Text;
-using Newtonsoft.Json;
 
 namespace Prophet.CoopWithDsh
 {
     internal sealed class SnapshotPublisher : IDisposable
     {
+        private static readonly DataContractJsonSerializer Serializer = new DataContractJsonSerializer(typeof(OpenFileSnapshot));
         private readonly object gate = new object();
         internal string InstanceId { get; } = Guid.NewGuid().ToString("N");
         internal string FilePath { get; }
@@ -26,7 +27,11 @@ namespace Prophet.CoopWithDsh
                 var directory = Path.GetDirectoryName(FilePath)!;
                 Directory.CreateDirectory(directory);
                 var temporary = FilePath + "." + Guid.NewGuid().ToString("N") + ".tmp";
-                File.WriteAllText(temporary, JsonConvert.SerializeObject(snapshot) + Environment.NewLine, new UTF8Encoding(false));
+                using (var stream = new MemoryStream())
+                {
+                    Serializer.WriteObject(stream, snapshot);
+                    File.WriteAllText(temporary, Encoding.UTF8.GetString(stream.ToArray()) + Environment.NewLine, new UTF8Encoding(false));
+                }
                 try
                 {
                     if (File.Exists(FilePath)) File.Replace(temporary, FilePath, null);