Add server api definition

MusicCast.Net.Api.Server/Models/GetDisklavierSettingsResponse.cs

@@ -0,0 +1,21 @@
+namespace MusicCast.Net.Api.Server.Models;
+
+public class GetDisklavierSettingsResponse
+{
+    public int response_code { get; set; }
+    public bool enable { get; set; }
+    public string mode { get; set; }
+    public string input { get; set; }
+    public Pair pair { get; set; }
+    public Disklavier disklavier { get; set; }
+
+    public class Pair
+    {
+        public string mac_address { get; set; }
+    }
+
+    public class Disklavier
+    {
+        public string ip_address { get; set; }
+    }
+}