[prop4n]

Makes the declared-but-unused spec.iso field actually attach an ISO to the VM as a cdrom drive, on ide0. The value is a Proxmox volume reference you upload yourself, e.g. local:iso/seed.iso.

Motivation: attach a NoCloud cidata ISO carrying custom user-data (any provider that reads a NoCloud datasource — cloud-init, guix-metadata, etc.). Generic, not tied to any distro.

• Attaches on blank, image, and clone paths.
• The Proxmox cloud-init drive (ide2) is now added only when cloudInit is set, so it never collides with a user-supplied cidata ISO (both label cidata). Set iso without cloudInit for the NoCloud flow; set cloudInit for the Proxmox-managed one.

Example:

spec:
  fromTemplate: guix-generic-tpl
  iso: local:iso/web01-seed.iso   # you upload it; carries the user-data
  state: running

Tests: iso option builder, iso propagates through the clone spec; full suite, lint, gofmt green.