Pair with NearTrace (deferred — S01E07)

Tracking issue: #381 The Phone-Pi Handshake.

The plan:

1. Pi advertises an _neartrace._tcp.local mDNS service on the management AP + USB tether interfaces.
2. The NearTrace Android app already runs an mDNS scanner (it surfaces LAN hosts in the SPECS tab — see the main NearTrace wiki). When it sees this service, the UI offers a "Connect to capture rig" affordance.
3. Phone becomes the wireless UI for monitor-mode capture, deauth detection, PCAP browsing — leveraging features the Play-store build can't have but the Pi can.

This page lights up when S01E07 ships. Until then: SSH it the old way (reach the rig).