Sync both server snapshots with what the live machines run, and keep their backup tooling

server/vps/server-backup.timer

@@ -0,0 +1,18 @@
+[Unit]
+Description=Daily backup of ~/Server to the home server
+
+[Timer]
+# MUST finish before the home server's cron.daily fires zfs-auto-snapshot, which has
+# been landing between 03:22 and 03:52. If the snapshot catches a half-finished rsync,
+# that day's history entry is a partial backup. 01:00 leaves >2h of margin; the first
+# full run took well under that and daily deltas are far smaller.
+OnCalendar=*-*-* 01:00:00
+# Small jitter only -- must not push us into the snapshot window.
+RandomizedDelaySec=10m
+# If the VPS was down at 01:00, run once after it comes back rather than
+# silently skipping a day.
+Persistent=true
+Unit=server-backup.service
+
+[Install]
+WantedBy=timers.target