The 1 Hz status push was silent at INFO, so support bundles couldn't show
whether the push task was actually reaching a specific slicer connection.
Now ``_periodic_status_push`` emits one line per minute per connected
slicer ("1Hz status push: N pushes/min to <client>") and stays silent when
no slicer is attached. No behaviour change to the push itself — counters
are local to the task and reset every 60 ticks.
Motivated by the open follow-up on #1548: keepalive parser shipped (b6636053)
and the symptom moved 60 s → 90 s, but OrcaSlicer still disconnects on idle.
This adds the missing observability so the reporter's next support bundle
shows whether our outbound 1 Hz push is alive for the disconnecting
connection.
maziggy
4ffefa60f4