Remove Portainer option and related install/helper functions. Add caching of downloaded OS images to /var/lib/vz/template/cache and use a temporary work qcow2 for customization. Try to preinstall qemu-guest-agent and Docker with virt-customize (marking DOCKER_PREINSTALLED on success) and provide a fallback first-boot install-docker.service script when customization fails. Replace import flow to detect qm disk import vs qm importdisk, import the prepared image into storage, resize the disk, attach EFI/root disks, and simplify VM creation steps. Include various UX/cleanup tweaks (spinner handling, storage import flags, status messages and Cloud-Init/SSH handling).