The chat notification FGS — and its mandatory persistent 'Waiting for
Hermes replies' notification — was started on every ON_STOP of the chat
screen, even when nothing was in flight, and lingered at app startup.
Track a pending-reply flag on HermesWsClient (set when a prompt is
submitted and on any in-flight turn event, cleared on MessageComplete),
gate NotificationHelper.start() on it, and have the service retire
itself after delivering the reply notification in the background.
Replies sent from the notification re-arm the service for the
follow-up turn.
Co-authored-by: M57 <hy4ri@users.noreply.github.com>
