Import Enums namespace conditionally in model template

Adds conditional import of the Enums namespace in the Model.cs.twig template only when the model definition contains enum properties. This prevents unnecessary imports and improves template clarity.

Author: Fellmonkey

templates/dotnet/Package/Models/Model.cs.twig

@@ -4,7 +4,9 @@ using System.Linq;
 using System.Collections.Generic;
 using System.Text.Json;
 using System.Text.Json.Serialization;
+{% if definition.properties | filter(p => p.enum) | length > 0 %}
 using {{ spec.title | caseUcfirst }}.Enums;
+{% endif %}
 
 namespace {{ spec.title | caseUcfirst }}.Models
 {