- vm-core.func: add rm -f WORK_FILE in all recovery paths (RETRY,
SKIP_CUSTOMIZE, RETRY_SETTINGS, NEW_VMID) to prevent multi-GB temp
file leaks in /tmp on failed retry
- debian-13-vm.sh: same WORK_FILE cleanup in inline recovery path
- debian-13-vm.sh: fix misleading 'will configure on first boot' msg
when skipping virt-customize (no first-boot mechanism exists)