Adds a new NetAlertX plugin that syncs known devices from the NetAlertX
database to AdGuard Home as persistent clients, keeping names, MACs, IP
addresses, and device-type tags in sync.
Also fixes the adguard_import config.json description placeholder and a
minor indentation inconsistency in that file.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>