Long-running gateways need the curator to fire on cadence without
restarts. Piggy-back on the existing cron ticker thread (which already
runs image/document cache cleanup every hour on the same pattern)
instead of spawning a dedicated timer thread.
- New CURATOR_EVERY = 60 ticks (poll hourly at default 60s interval).
The inner config.interval_hours gate controls the real cadence, so
60 of these 60 hourly pokes are cheap no-ops and one runs the review.
- Removed the boot-time call added in the prior commit — the ticker
covers boot + every hour thereafter. Avoids double-running.
Handles the weekly-default-on-24/7-gateway gap flagged in review.
019d4c1c3f