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.
