[yuravk]

Closes #376

Why

VirtualBox 7.1+ runs arm64 guests on Apple Silicon Macs, but the almalinux/9 and almalinux/10 Vagrant boxes ship VirtualBox images for amd64 only (arm64 exists only for vmware_desktop and parallels). No runner can run VirtualBox ARM guests, so the box is built the way the Parallels aarch64 box is (#370): installed and provisioned under QEMU, then packed into a virtualbox box.

What

• Packer: new qemu sources almalinux-9-virtualbox-aarch64, almalinux_10_vagrant_virtualbox_qemu_aarch64 and almalinux_kitten_10_vagrant_virtualbox_qemu_aarch64 (virtio-scsi, copies of the Parallels ones). Packer uploads the Guest Additions ISO (virtualbox_guest_additions_iso_aarch64) and provisions the guest as a VirtualBox box (packer_provider=virtualbox-iso).
• Guest Additions: new virtualbox_guest_arm64 role, used on aarch64 (ezamriy.vbox_guest stays for x86_64; it only runs the x86 installer). It installs the build dependencies including kernel-devel of the running kernel, runs VBoxLinuxAdditions-arm64.run, and checks that vboxguest/vboxsf were built - under QEMU the installer builds the modules but cannot start its services, so its exit code is not used. Build dependencies and installer logs are removed afterwards.
• Box: tools/raw-to-vagrant-virtualbox.sh converts the raw disk to a streamOptimized VMDK and renders box.ovf from tpl/vagrant/virtualbox/box-aarch64.ovf - exported by VirtualBox 7.2 itself from an ARM VM of its defaults for Red Hat 9.x/10.x ARM 64-bit (ARMv8Virtual chipset, EFI, VirtioSCSI disk, virtio NIC on NAT, 2 vCPUs / 2048 MB), with fresh UUIDs and MAC. Like the x86_64 box it has a Vagrantfile with base_mac and metadata.json with the architecture (arm64).
• Workflow: virtualbox-aarch64 leg of build-gh-hosted for vagrant_type ALL or vagrant_virtualbox (not for AlmaLinux 8, excluded for the -v2 variants), run_test forced off like the other QEMU-built boxes. Guest Additions 7.2.20 (the first release whose vboxsf builds on the EL10/Kitten 6.12 kernels) are downloaded from download.virtualbox.org and checked against Oracle's SHA256SUMS. In the AlmaLinux org the leg builds natively on the arm64 runners, and publish-aarch64 picks it up.
• Resolver (virtualbox_* cases), shared-steps raw-disk validation, kickstart comments and VAGRANT_BUILD_TEST_PUBLISH.md updated.

Testing

All three boxes built in ci-dev from this commit; the aarch64 legs run natively on the arm64 runners (~18-23 min), and the x86_64 VirtualBox legs of the same runs are unaffected:

Box	Run	Kernel the Guest Additions 7.2.20 were built for	Box size
AlmaLinux 9.8	38382539889	5.14.0-687.54.1.el9_8.aarch64	536 MB
AlmaLinux 10.2	38533104835	6.12.0-211.65.1.el10_2.aarch64	624 MB
AlmaLinux Kitten 10	38538092173	6.12.0-273.el10.aarch64	596 MB

• vboxguest and vboxsf are built and the vboxadd services enabled in every box; vboxvideo too on 9 and 10 (the installer skips it on the Kitten kernel - not needed by a headless box). Offline validation passed for all three.

• Each box imports into VirtualBox 7.2.16 and through vagrant up as an ARM VM with the expected settings (checked on an x86_64 host, where only the boot itself is impossible). No -v2 aarch64 leg is created.

• Verified on Apple Silicon by the reporter (add VirtualBox aarch64 (arm64) Vagrant boxes #376) for all three boxes: macOS 26.6.2, VirtualBox 7.2.20, Vagrant 2.4.9 - each boots, vagrant ssh works, /vagrant is mounted via vboxsf (rw), with vboxguest/vboxsf loaded on 5.14.0-687.54.1.el9_8, 6.12.0-211.65.1.el10_2 and 6.12.0-273.el10.

• packer fmt/packer validate (all three sources), shellcheck, YAML parse.

The box's OVF uses VirtualBox 7.2's settings format (1.20); import into VirtualBox 7.1 is untested.