feat: enable autostart for runner and k3s VMs

[xnoto]

Summary

• Sets autostart = true on the runner and k3s module calls, opting both libvirt domains into libvirtd's start-on-boot behavior
• Consumes the new autostart input added in terraform-libvirt-domain#6
• router is not managed by this tfroot — its autostart flag was set manually on hero (sudo virsh autostart router)

Test plan

• opentofu workflow green (validate, fmt, tflint, plan)
• Plan diff shows + autostart = true on module.runner.libvirt_domain.vm and module.k3s.libvirt_domain.vm, no other in-place updates
• After apply on hero: sudo virsh dominfo k3s | grep Autostart and runner both report enable

🤖 Generated with Claude Code

[github-actions]

OpenTofu Plan

OpenTofu will perform the following actions:

  # module.k3s.libvirt_cloudinit_disk.commoninit will be created
  + resource "libvirt_cloudinit_disk" "commoninit" {
      + id             = (known after apply)
      + meta_data      = <<-EOT
            instance-id: k3s
            local-hostname: k3s
        EOT
      + name           = "k3s_commoninit"
      + network_config = <<-EOT
            version: 2
            ethernets:
              enp1s0:
                dhcp4: true
              enp2s0:
                dhcp4: false
                addresses:
                  - 192.168.102.2/24
        EOT
      + path           = (known after apply)
      + size           = (known after apply)
      + user_data      = (sensitive value)
    }

  # module.k3s.libvirt_volume.cloudinit will be updated in-place
  ~ resource "libvirt_volume" "cloudinit" {
      ~ allocation = 49152 -> (known after apply)
      ~ capacity   = 49152 -> (known after apply)
      ~ create     = {
          ~ content = {
              ~ url = "/home/user/terraform-provider-libvirt-cloudinit/cloudinit-16de859e0abe38bb.iso" -> (known after apply)
            }
        }
        id         = "/mnt/nvme/cluster/k3s_cloudinit.iso"
        name       = "k3s_cloudinit.iso"
      ~ physical   = 49152 -> (known after apply)
        # (3 unchanged attributes hidden)
    }

  # module.runner.libvirt_cloudinit_disk.commoninit will be created
  + resource "libvirt_cloudinit_disk" "commoninit" {
      + id             = (known after apply)
      + meta_data      = <<-EOT
            instance-id: runner
            local-hostname: runner
        EOT
      + name           = "runner_commoninit"
      + network_config = (sensitive value)
      + path           = (known after apply)
      + size           = (known after apply)
      + user_data      = (sensitive value)
    }

  # module.runner.libvirt_volume.cloudinit will be updated in-place
  ~ resource "libvirt_volume" "cloudinit" {
      ~ allocation = 49152 -> (known after apply)
      ~ capacity   = 49152 -> (known after apply)
      ~ create     = {
          ~ content = {
              ~ url = "/home/user/terraform-provider-libvirt-cloudinit/cloudinit-86070e4489865a53.iso" -> (known after apply)
            }
        }
        id         = "/var/lib/libvirt/images/runner_cloudinit.iso"
        name       = "runner_cloudinit.iso"
      ~ physical   = 49152 -> (known after apply)
        # (3 unchanged attributes hidden)
    }

Plan: 2 to add, 2 to change, 0 to destroy.