Backend:
- ProtectedDevice prisma model + migration add_protected_devices
- DB helpers: list/count/get/create/confirm/revoke
- mobileconfig.ts utility — XML-escape, unique UUIDs per request
- 5 endpoints under /api/devices/* (avoid /api/devices conflict with existing
Capacitor UserDevice route by using /api/devices/protected for list)
Phase 1: backend ready. DoH-server token-routing comes in phase 2.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>