VM image: one file, named like the ISO

The image was a folder, vm/, holding base.qcow2 and what boots it. It is
now one file next to the ISO, with the ISO's name and its own checksum
file, the way Ubuntu, Debian, Arch, Fedora and CentOS publish theirs:

  edge/<version>/omarchy-edge-<version>.qcow2
  stable/<version>/<run>/omarchy-<version>.qcow2

The image boots by itself through UEFI. What a direct boot needs, the
kernel, initramfs, kernel arguments and vm-boot, is in an unpacked/
folder beside it, Ubuntu's name for the same thing. The firmware
variables are no longer published: a boot with the firmware's defaults
finds the disk.

latest.json follows: vm.url, vm.sha256 and vm.size are the image, as
url, sha256 and size are the ISO; vm.unpacked and vm.unpacked_files are
the folder. vm-boot takes the image file. The publish job compares every
file it uploaded, whatever the layout. README, tests and the workflow's
header say the same.

test/vm-image/vm-boot

@@ -1,11 +1,16 @@
 #!/bin/bash
 # Boots a sealed Omarchy image (vm-seal) as a throwaway machine.
 #
-#   vm-boot <sealed_dir>                 boot, print how to log in, run until Ctrl-C
-#   vm-boot <sealed_dir> <command...>    boot, run the command over SSH, power off;
-#                                        exits with the command's status
+#   vm-boot <image>                 boot, print how to log in, run until Ctrl-C
+#   vm-boot <image> <command...>    boot, run the command over SSH, power off;
+#                                   exits with the command's status
 #
-# Nothing is written to sealed_dir: the machine runs on a copy-on-write overlay
+# <image> is a downloaded disk, omarchy-<...>.qcow2, with vmlinuz, initrd and
+# cmdline in the same directory as this script, as in a published "unpacked"
+# folder. Or it is a directory as vm-seal leaves it, holding base.qcow2 and
+# those three files.
+#
+# Nothing is written to the image: the machine runs on a copy-on-write overlay
 # that is deleted on exit. Each boot gets a new SSH key and a new machine ID;
 # the image itself holds no key and its SSH takes no password.
 #
@@ -14,9 +19,15 @@
 #      kernel arguments), QEMU_EXTRA (more qemu arguments, split on spaces),
 #      VM_STATE_DIR (/var/tmp; holds the overlay, so it needs room to grow).
 set -euo pipefail
-[[ $# -ge 1 ]] || { sed -n '2,16p' "$0" >&2; exit 2; }
-base=$(realpath "$1"); shift
-for f in base.qcow2 vmlinuz initrd cmdline; do
+[[ $# -ge 1 ]] || { sed -n '2,21p' "$0" >&2; exit 2; }
+image=$(realpath "$1"); shift
+if [[ -d $image ]]; then
+  base=$image disk=$image/base.qcow2
+else
+  base=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd) disk=$image
+fi
+[[ -s $disk ]] || { echo "vm-boot: there is no disk image at $disk" >&2; exit 1; }
+for f in vmlinuz initrd cmdline; do
   [[ -s $base/$f ]] || { echo "vm-boot: $base/$f is missing" >&2; exit 1; }
 done
 [[ -r /dev/kvm && -w /dev/kvm ]] || { echo "vm-boot: /dev/kvm is not usable" >&2; exit 1; }
@@ -45,7 +56,7 @@ keys=$(printf 'd /home/omarchy/.ssh 0700 omarchy omarchy -\nf+ /home/omarchy/.ss
 ssh_opts=(-i "$state/id_ed25519" -p "$port" -o BatchMode=yes -o IdentitiesOnly=yes
   -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o LogLevel=ERROR)
 
-qemu-img create -qf qcow2 -b "$base/base.qcow2" -F qcow2 "$state/run.qcow2"
+qemu-img create -qf qcow2 -b "$disk" -F qcow2 "$state/run.qcow2"
 t0=$(date +%s%N)
 # shellcheck disable=SC2086
 qemu-system-x86_64 -cpu host -enable-kvm -machine q35,accel=kvm -smp "${SMP:-4}" -m "${MEM:-4G}" \