-- Backup retention is OPERATIONAL POLICY the on-site admin tunes from the Backup screen, not a
-- server env var requiring a redeploy. Two additive, nullable columns on the single-row config;
-- null = fall back to the code default (keepLast 7, keepDailyDays 30). The backup ENGINE stays
-- parameterized; this just moves the source of truth env → DB. See wiki/concepts/backup-recovery.md.
ALTER TABLE `site_config` ADD `backup_keep_last` integer;--> statement-breakpoint
ALTER TABLE `site_config` ADD `backup_keep_daily_days` integer;