Bb.3 - One global scanner; Mini Apps register as QR handlers

A single native scanner routes any QR code, a crypto payment, a Lightning invoice, a local scheme like Vietnam’s VietQR, to the Mini App that can handle it, instead of forcing you to open the right app first. Mini Apps register themselves as handlers for the codes they understand. If no installed Mini App can pay a code but one exists in the catalog, the scanner can offer to install it (Bb.6).