QR Code Display + Add to Google Wallet Button

[NoNathan17]

Description

Add a check-in QR code display and an Add to Google Wallet button to ZotHacks applicant portal near the QR code after the user has been RSVPed to the hackathon. The button should call the backend endpoint and redirect the applicant to the Google Wallet save URL.

The QR code and Google Wallet pass should both encode the same value: the applicant's identity.uid.

[!NOTE] This issue is blocked by the corresponding issue

Acceptance Criteria

• Button is shown near the QR code
• Button only appears if the user has RSVPed with CONFIRMED status
• Button calls GET /api/user/google-wallet-pass
• If saveUrl is returned, user is redirected to it
• Errors are handled gracefully

Resources

Google Wallet Documentation