Install the VirtIO Arm64 drivers with pnputil; make OpenSSH a batch file

On Arm64 Windows the VirtIO guest tools installer is an x86 program and the
VirtIO ISO has no Arm64 package for it, so the first-logon script failed there
and the guest had no network (no NetKVM driver). Install the Arm64 NetKVM,
vioserial, Balloon, viorng and vioinput drivers from their folders on the ISO
with pnputil instead.

The OpenSSH Server capability is downloaded through Windows Update, which can
take very long and blocked the rest of the script. Move it, with the
administrator authorized key, into 05-Install-OpenSSH-Admin.bat, which the
script copies to the Installers folder on the desktop to run by hand.

Update the vm-images submodule to the build script that runs on Debian.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

README.md

@@ -168,13 +168,17 @@ from the shared Windows 11 QCOW2 base image:
 It creates a persistent 64G disk at `.vm/windows11/disk.qcow2`, automatically
 partitions it, completes OOBE, creates the local administrator `guofang` with
 the initial password `wang`, and enables Remote Desktop on
-`localhost:3389`. During the first login it also installs and enables the
-Windows OpenSSH Server on `localhost:2222` and silently installs the VirtIO
-Windows guest tools. It also installs the host's configured SSH public key for
-passwordless administrator login. The installer includes the VirtIO drivers, SPICE vdagent,
-and QEMU Guest Agent. Connect with `ssh guofang@localhost -p 2222`. The launcher
-exposes the vdagent channel for host/guest clipboard integration and the QEMU Guest Agent at
-`.vm/windows11/qemu-guest-agent.sock`. Change the password after first login.
+`localhost:3389`. During the first login it also silently installs the VirtIO
+drivers (the guest tools installer on amd64, the Arm64 driver packages from the
+VirtIO ISO with `pnputil` on arm64), without which the guest has no network on
+arm64. The installer includes the VirtIO drivers, SPICE vdagent, and QEMU Guest
+Agent. The launcher exposes the vdagent channel for host/guest clipboard
+integration and the QEMU Guest Agent at `.vm/windows11/qemu-guest-agent.sock`.
+Change the password after first login. The OpenSSH Server is downloaded through
+Windows Update, which can be slow, so it is not installed automatically: run
+`05-Install-OpenSSH-Admin.bat` from the `Installers` folder on the desktop as
+administrator, then connect with `ssh guofang@localhost -p 2222`; it also installs
+the host's configured SSH public key for passwordless administrator login.
 The Windows VM hardware (8G memory, 8 CPUs, system disk, devices)
 is defined in `qemu/windows11.ini`, with the accelerators and machine type in
 `qemu/windows11-<os>-<arch>.ini`; the launcher renders the former to