[Feature] bring back optimal confidence threshold in metrics page

Created by: olkham

📄 Description

I can't see where the selected threshold for a detection model is in the UI. It's a really important value for us to know. I can only find it in the xml, which is super laborious to download, extract the zip, navigate to and open each time.

🎯 Objective

Make the model metrics more useful. Common metrics and params are absent but there are tons of obscure ones that have no explanation and are often just stuck at fixed values anyway so offer no insight.