feat: let users publish models (and jsons) to the hub

[0xSage]

Problem

• model.json is easily packageable /exportable. Let users share it via the hub

Success Criteria A clear and concise description of what you want to happen.

• Users can share their models via hub (just the download URL, as we dont host models yet)
• Users can share their model configs via hub

Additional context Add any other context or screenshots about the feature request here.