RMS Digital Contact QR - Patch All Staff QR Gallery

New admin page: /admin/qr_gallery.php
Features:
- View QR for all ACTIVE staff on one page
- QR resize slider 120px - 360px
- 2 / 3 / 4 / 5 column layouts
- Search and sector filter
- Print all QR using current size/layout
- Open individual QR and Contact Card
- Admin view preference saved in browser localStorage

No database changes required.
