Add IP roaming reconciliation for active devices during network scan ...

- Extract reconcile_scan_results() into Devices model: updates device_ip
  and restores connection_status='active' when a known device is found on
  a different IP address.
- Refactor CronController to use the shared method.
- Also call reconcile_scan_results() in DevicesRESTAPIController::scanning__all()
  so manual scans from the UI update roaming device IPs.
- Add DevicesTest with coverage for IP update + lost device restore.
- Fix test bootstrap: remove non-existent SHServ\Sessions reference.