Add application_type to the Dynamic Client Registration request (#1613)

tests/ModelContextProtocol.TestOAuthServer/ClientRegistrationRequest.cs

@@ -55,6 +55,12 @@ internal sealed class ClientRegistrationRequest
     [JsonPropertyName("scope")]
     public string? Scope { get; init; }
 
+    /// <summary>
+    /// Gets or sets the OIDC application type ("web" or "native").
+    /// </summary>
+    [JsonPropertyName("application_type")]
+    public string? ApplicationType { get; init; }
+
     /// <summary>
     /// Gets or sets the contacts for the client.
     /// </summary>