llm: add service.ModelName
diff --git a/llm/oai/oai.go b/llm/oai/oai.go
index 8b64157..4b046b0 100644
--- a/llm/oai/oai.go
+++ b/llm/oai/oai.go
@@ -225,6 +225,10 @@
 
 var _ llm.Service = (*Service)(nil)
 
+func (s *Service) ModelName() string {
+	return s.Model.UserName
+}
+
 // ModelsRegistry is a registry of all known models with their user-friendly names.
 var ModelsRegistry = []Model{
 	GPT41,