Convert DaemonOutbound::Heartbeat from unit to struct variant with two
optional fields advertising the daemon's T2 reachability. Old payloads
({"type":"Heartbeat"} with no fields) still parse — both fields default
to None — and a new daemon that doesn't populate them serializes back to
the same minimal shape.
Update the daemon's heartbeat ticker and the registry's match arm to the
new shape. Population from daemon config + registry persistence lands
with the broker logic in NAP-243.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
naps62-yoloandClaude Opus 4.7
9a8109559b