Gift vouchers: Quality of life updates

This update includes fixes for several minor issues discovered during the initial rollout of gift vouchers, plus various quality of life updates:

• Resolved an issue where the order notification email would not be sent to site administrators under certain conditions.
• Fixed a bug with the page preview functionality when previewing changes to a gift voucher's page.
• Corrected a bug with the QR code scanner that caused the front camera to open instead of the rear camera on some mobile devices.
• Temporarily disabled push notifications for gift voucher orders while we debug an issue. Other notifications for new orders remain active.
• Fixed an issue in the site navigation manager where adding voucher pages to the navigation resulted in encoded text being displayed.
• Reviewed error logs and implemented fixes for all logged issues. No critical issues were discovered during our review.