Make Nextcloud NAS backups independent, verified and retryable

systemd/user/nextcloud-borg-backup.service

@@ -1,13 +1,20 @@
 [Unit]
-Description=Back up mounted Nextcloud folder to Synology with Borg
+Description=Verified Nextcloud backup to NAS (independent of desktop mount)
 Documentation=man:borg(1)
+StartLimitIntervalSec=0
 
 [Service]
 Type=oneshot
-ExecStart=%h/.local/bin/nextcloud-borg-backup backup
+ExecStart=%h/.local/bin/nextcloud-borg-backup backup --if-due
 TimeoutStartSec=12h
+TimeoutStopSec=30s
+KillMode=control-group
 Nice=10
 IOSchedulingClass=best-effort
 IOSchedulingPriority=6
+UMask=0077
+NoNewPrivileges=true
 Environment=LANG=C.UTF-8
 Environment=LC_ALL=C.UTF-8
+Environment=BORG_LOCK_WAIT=60
+Environment=BORG_NON_INTERACTIVE=1