Persistent MAC-keyed lan_devices store fed by an hourly arp-scan on CT 311;
diffs new vs known, mirrors the services discovered→promote flow for naming/
editing. Upsert-by-MAC keeps the table bounded. Borrows decoupled-scanner +
MAC-identity lessons from scanopy.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
