ONE setting (window start W) drives every nightly leg at fixed, never-stored
offsets: DB dump at W, tier-2 at W+60m, off-box at W+105m (wrap-safe). Precedence
settings > controller.yaml db_dump_schedule > 02:30.
- scheduler.UpdateDaily: retime a daily job at runtime (no restart) via a per-job
buffered resched chan + a select case in runDailyJob.
- new pure package internal/backupwindow (LegTimes/GateWindow/EffectiveWindow).
- quiesce disk-tier window gate: scheduled cycles run only inside [W+2h,W+6h) with a
safety valve (age>cadence+24h runs regardless); manual TriggerNow never gated.
Backend.Due now also returns the backup age (from the agent's own /backup/due).
- backup page: Mentési időablak card (time input + derived leg/gate rows); POST
/backups/window validates -> saves -> UpdateDaily x3 -> flash.
Tests: 5 groups, all red-proofed. Agent/cadence//backup/due untouched.