safeguard: check Docker/VM Manager enabled before acting

common.sh: add is_docker_enabled() and is_vm_manager_enabled() helpers
reading /boot/config/docker.cfg and /boot/config/domain.cfg.

docker_watchdog: exit cleanly if Docker not enabled in Unraid settings.
stability_watchdog: skip Docker daemon check and Docker container stop
if Docker not enabled; skip virsh VM shutdown if VM Manager not enabled.
server_reboot: skip VM shutdown and libvirt stop if VM Manager not enabled.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

unRAID_Essentials/server_reboot.sh

@@ -252,7 +252,7 @@ fi
 # ==============================================================================================
 # ━━━ Graceful VM Shutdown ━━━
 # ==============================================================================================
-if command -v virsh >/dev/null 2>&1; then
+if is_vm_manager_enabled && command -v virsh >/dev/null 2>&1; then
     VM_LIST=$(virsh list --name 2>/dev/null | grep -v "^$" || true)
     if [[ -n "$VM_LIST" ]]; then
         echo ""
@@ -272,7 +272,11 @@ if command -v virsh >/dev/null 2>&1; then
             log "Waiting ${VM_WAIT}s for VMs to shut down..."
             sleep "$VM_WAIT"
         fi
+    else
+        log "VM Manager enabled but no VMs running — skipping shutdown"
     fi
+else
+    log "VM Manager not enabled — skipping VM shutdown"
 fi
 
 # ==============================================================================================
@@ -280,7 +284,9 @@ fi
 # ==============================================================================================
 echo ""
 echo "━━━ $ICON_GEAR Stop VM Manager ━━━"
-if [[ "$DRY_RUN" == true ]]; then
+if ! is_vm_manager_enabled; then
+    log "VM Manager not enabled — skipping"
+elif [[ "$DRY_RUN" == true ]]; then
     warn "DRY RUN — would stop VM Manager (libvirt)"
 else
     if /etc/rc.d/rc.libvirt stop >/dev/null 2>&1; then