Replaces the template-clone flow with: create empty VM shell, download the
cloud image on the node (cached by filename, optional checksum verification),
qm importdisk, attach as scsi0. NIC config, snippet upload, ssh keys, disk
resize, and start remain unchanged (already generic).
New helpers: _run_node_command (strict SSH exec with custom timeout and
non-zero-exit detection, unlike the best-effort _exec_ssh_command),
_download_cloud_image (idempotent download + checksum check),
_find_default_image_storage (content=images discovery, mirrors the existing
snippet-storage discovery).
24 tests pass (10 new: _run_node_command x2, _download_cloud_image x4, plus
rewrites of the 4 existing create_vm_from_cloud_init tests for the new flow).
Filters _get_node_network() to bridge/OVSBridge types only (excludes physical
NICs, bonds), plus SDN vnets from _get_sdn_vnets(). vlan_aware: Linux bridge
reflects its bridge_vlan_aware config flag; OVS bridge always true; SDN vnet
always false (VLAN already fixed by the vnet's zone/tag).
4 new tests: bridge/vnet filtering, Linux bridge vlan_aware flag, OVS bridge
always vlan_aware, SDN vnet never vlan_aware. All 15 tests in the file pass.
Test cases: single/dual NIC with VLAN tags or trunk config, per-NIC DHCP control,
disk resize parameter, snippet storage validation, IP wait timeout, destroy paths.
All TDD cases green.
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>