Backend fixes for VM/LXC disk resize:
- resize_vm_disk/resize_container_disk now honor wait_for_task and raise
the real Proxmox exitstatus (e.g. "disk 'scsi0' does not exist") instead
of always returning success.
- add grow_vm_filesystem: after a VM resize, rescan the disk (retry loop,
needed for SATA/SCSI), growpart the partition and resize the FS
(ext*/xfs/btrfs) via the guest agent; surface its output to the API.
- execute_script normalizes CRLF/CR to LF so pasted scripts and growpart
don't break on trailing \r ("partition-number must be a number").
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>