Stop a running desktop display manager during a live install

On a Pi OS Desktop image lightdm keeps display :0 until the next reboot,
so the kiosk X server failed with 'server already running'. Disabled
display managers are recorded and re-enabled by uninstall.sh.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

uninstall.sh

@@ -20,6 +20,7 @@ UNITS=(voxip-kiosk-healthcheck.timer voxip-kiosk-healthcheck.service voxip-kiosk
        voxip-network-guard.service voxip-boot-import.service)
 
 PREVIOUS_TARGET="$(cat /var/lib/voxip-kiosk/previous-default-target 2>/dev/null || true)"
+mapfile -t DISABLED_DMS < <(cat /var/lib/voxip-kiosk/disabled-display-managers 2>/dev/null)
 
 echo "==> Services stoppen en verwijderen"
 systemctl stop voxip-network-rollback.timer 2>/dev/null || true
@@ -62,4 +63,5 @@ else
 fi
 
 if [[ -n $PREVIOUS_TARGET ]]; then systemctl set-default "$PREVIOUS_TARGET" >/dev/null 2>&1 || true; fi
+for dm in "${DISABLED_DMS[@]}"; do systemctl enable "$dm" >/dev/null 2>&1 || true; done
 echo "==> VoxIP Kiosk OS is verwijderd. Herstart de Raspberry Pi om de kiosk te stoppen."