Support arm64 hosts in the Windows 11 launcher

Pick qemu-system-aarch64, the AArch64 UEFI firmware and a per-architecture
QEMU config (NVMe disk, virtio-net, ramfb, USB installation media) on arm64,
render the answer file for the target architecture, and move the q35-only
disk and NIC devices out of the shared config. Update vm-images to match
arm64 Windows ISO names.

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

qemu/windows11-amd64.ini

@@ -2,3 +2,16 @@
 
 [machine]
   type = "q35"
+
+# The system disk is attached through IDE so that Windows can boot before the
+# VirtIO storage driver is installed; the installation media of
+# --install-from-iso use ide.1 to ide.3.
+[device "system_disk-dev"]
+  driver = "ide-hd"
+  drive = "system_disk"
+  bus = "ide.0"
+  bootindex = "1"
+
+[device "nic0"]
+  driver = "e1000e"
+  netdev = "net0"