Adds ScheduleConfig + NextFire (per-mode logic for off/interval/
daily/weekly) and the Scheduler struct + loop goroutine. The loop
reads scan_schedule on boot and on Refresh signals, computes
next-fire, sleeps via time.Timer, and calls TryStartScan when the
timer fires. Skip-on-conflict logging happens inside tryFire when
TryStartScan reports started=false with a non-stale in-flight row.
Boot wiring: cmd/minstrel/main.go constructs the scheduler after
coverEnricher and calls Start with the server's long-lived ctx.
The scheduler is not yet plumbed into the HTTP handlers (the next
task does that — handlers gain a scheduler field, admin schedule
endpoints land).
Tests cover the NextFire truth table (off / interval / daily today
+ tomorrow / weekly today-before-time + today-after-time + upcoming
day) plus invalid configs and parseHHMM edge cases. Refresh is
verified non-blocking via the buffered-channel + default pattern.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
bvandeusen
4607ce6db4