fix model arg

Author: mythz

AiServer.ServiceInterface/Comfy/ComfyClient.cs

@@ -142,6 +142,7 @@ public async Task<string> PopulateWorkflowAsync(Dictionary<string,object> args,
         // Populate template with request
         var workflowPageResult = new PageResult(context.OneTimePage(template)) {
             Args = args,
+            Model = args.GetValueOrDefault("model"),
         };
 
         // Render template to JSON