feat: add remote device management and pairing functionality

- Implemented device pairing with a four-digit code and TTL for remote settings.
- Introduced automatic checks for device status and configuration validation.
- Developed UI components for device setup and management, including error handling and retry options.
- Created a device bridge for secure communication between the device and the server.
- Added tests for managed state validation and device pairing logic.
- Established a local end-to-end fixture for testing device service and API interactions.

.env.example

@@ -11,3 +11,9 @@ BOARD_PWA_URL=https://pwa.ridebus.by/
 OPEN_METEO_API_KEY=
 PORT=5180
 HOST=127.0.0.1
+# Managed displays: pair each browser in the admin's Devices section.
+BOARD_REMOTE_SETTINGS=false
+# Optional URL shown on the pairing screen.
+BOARD_ADMIN_URL=
+# Set true behind an HTTPS reverse proxy if it does not send X-Forwarded-Proto.
+BOARD_COOKIE_SECURE=false