feat(vikon): move API token from .env to integration_credentials

- Rename VICON_TOKEN → VIKON_API_TOKEN in .env and config
- Add ViconApiToken service reading from integration_credentials table
- Update 3 Vicon services to use ViconApiToken instead of config()
- Config/env kept as fallback for clean migration

example.env

@@ -62,4 +62,4 @@ VITE_PUSHER_PORT="${PUSHER_PORT}"
 VITE_PUSHER_SCHEME="${PUSHER_SCHEME}"
 VITE_PUSHER_APP_CLUSTER="${PUSHER_APP_CLUSTER}"
 
-VICON_TOKEN=
+VIKON_API_TOKEN=