kveton makes the demo budget stop hiding when users plug in their own key

On CaseMark's fork of the hosted demo, the credit-budget card used to vanish the moment a user pasted in their own Case.dev API key. The credits were still there in the background - the user just couldn't see them. kveton's fix keeps the card on screen whenever demo mode is on, and adds a label making clear that a personal key is now footing the bill and the demo allowance is sitting idle.

It's a presentation tweak, not a re-architecture - but it removes a small moment of confusion that matters in any product where users juggle a free tier and their own billed account.