fix: add UseAspNetCore() to OpenIddict validation

- Add .UseAspNetCore() to validation configuration
- This enables OpenIddict Server to properly process OAuth2 requests
- Fix for 'The OpenID Connect request cannot be retrieved' error

Configuration/OpenIddictSetup.cs

@@ -47,6 +47,7 @@ public static class OpenIddictSetup
         builder.AddValidation(options =>
         {
             options.UseLocalServer();
+            options.UseAspNetCore();
         });
 
         services.AddAuthentication(options =>