Say the heartbeat's interval, export the host's validator, grant the genesis controller Phase 1 (hq to-be 45)

The controller's watchdog of a machine's heartbeat (S1) is bound to three
of its intervals, and a bound the controller guessed would not move when
the interval does: the heartbeat now carries interval_seconds.

Its self-check (D1) must judge every composed declaration as the host
does, and a second validator written from the host's rules would drift
from them: the host's own parsing is exported, unchanged, as
github.com/novox/mesh-host/validate.

The installer's first user list grants what the controller now composes
for itself: its condition buckets, the condition and doctor-heartbeat
events, the bus's two consumer advisories and $SRV.INFO — or the first
controller would be refused them until the broker's machine is pushed.

internal/link/run.go

@@ -514,7 +514,7 @@ func publishReport(ctx context.Context, bus Bus, m Membership, report Report,
 // publishAlive says this node is here, and nothing else.
 func publishAlive(ctx context.Context, bus Bus, m Membership, say Announce,
 	timeout time.Duration) {
-	body, err := json.Marshal(Alive{Node: m.Node})
+	body, err := json.Marshal(Alive{Node: m.Node, IntervalSeconds: int(AliveEvery / time.Second)})
 	if err != nil {
 		return
 	}