QR Code Scanning Leads to JSON Instead of Universal Link with Fallback Page

[DibranMulder]

Problem
Currently, when users scan a QR code with their device's camera app (instead of the Yivi app), they may encounter a raw JSON response rather than being directed to the universal link. This results in confusion and a poor user experience.

Expected Behavior
The QR code should:

1. Point to the universal link. When scanned, the link should direct users to a functional fallback page if the Yivi app is not installed.
2. Provide a fallback page experience. The fallback page should guide users on how to install and configure the Yivi app or proceed with their flow.

Current Challenges
JSON Value Display: Scanning the QR code with a regular camera app shows the raw JSON instead of linking to the universal link.
Missing Fallback Page: The universal link currently lacks a proper fallback page, leading to usability issues when the app is not installed.

[ivard]

If you make this change, it's nice to also migrate from the irma.app universal link to the open.yivi.app universal link. That one should already work and it looks a little bit nicer then.