fix model reloading

ensure runtime model changes (template, system prompt, messages,
options) are captured on model updates without needing to reload the
server

llm/server.go

@@ -679,7 +679,7 @@ type CompletionRequest struct {
 	Prompt  string
 	Format  string
 	Images  []ImageData
-	Options api.Options
+	Options *api.Options
 }
 
 type CompletionResponse struct {