fix: Update v2 config detection criteria

Changed the logic for identifying v2 configuration files. The check now looks for the presence of a "versions" node instead of the absence of "system" or "template" nodes, reflecting an update in the configuration file structure.

src/PepperDash.Essentials.Core/Config/Essentials/ConfigReader.cs

@@ -129,10 +129,10 @@ namespace PepperDash.Essentials.Core.Config
                     {
                         var parsedConfig = JObject.Parse(fs.ReadToEnd());
 
-                        // Check if it's a v2 config (missing "system" or "template" nodes)
+                        // Check if it's a v2 config (check for "version" node)
                         // this means it's already merged by the Portal API
                         // from the v2 config tool
-                        var isV2Config = parsedConfig["system"] == null || parsedConfig["template"] == null;
+                        var isV2Config = parsedConfig["versions"] != null;
                         
                         if (isV2Config)
                         {