ci: run the install test with QEMU 11 in an Arch container

The harness now runs in archlinux:latest with /dev/kvm passed through,
so CI uses Arch's current QEMU and OVMF (QEMU 11.1, edk2 202608) at the
paths the harness expects, the same as an Omarchy workstation, instead
of Ubuntu 24.04's QEMU 8.2 with symlinks and shims. Arch splits QEMU's
devices into modules: virtio-vga needs both qemu-hw-display-virtio-gpu
and qemu-hw-display-virtio-vga, and QEMU 11.1 segfaults on
-device virtio-vga when only the latter is installed.

.github/workflows/install-test.yml

@@ -34,34 +34,28 @@ jobs:
           avail_gb=$(df -BG --output=avail / | tail -1 | tr -dc 0-9)
           [ "$avail_gb" -ge 40 ] || { echo "::error::only ${avail_gb} GB free, the ISO build and install test need ~40 GB"; exit 1; }
 
-      - name: Prepare the runner for KVM guests
-        run: |
-          sudo apt-get update -qq
-          sudo apt-get install -y -qq --no-install-recommends \
-            qemu-system-x86 qemu-utils ovmf socat imagemagick \
-            tesseract-ocr tesseract-ocr-eng mtools dosfstools jq openssh-client
-          # test/integration installs its tools through Omarchy's Arch helper;
-          # they are installed above.
-          printf '#!/bin/sh\nexit 0\n' | sudo tee /usr/local/bin/omarchy-pkg-add >/dev/null
-          sudo chmod 0755 /usr/local/bin/omarchy-pkg-add
-          # Keep the harness's Arch paths: map Ubuntu's OVMF files onto them.
-          sudo install -d /usr/share/edk2/x64
-          sudo ln -sf "$(find /usr/share -name 'OVMF_CODE_4M.fd' -print -quit)" /usr/share/edk2/x64/OVMF_CODE.4m.fd
-          sudo ln -sf "$(find /usr/share -name 'OVMF_VARS_4M.fd' -print -quit)" /usr/share/edk2/x64/OVMF_VARS.4m.fd
-          # Ubuntu's ImageMagick 6 is `convert`; the harness calls `magick`.
-          command -v magick >/dev/null || sudo ln -sf "$(command -v convert)" /usr/local/bin/magick
-          sudo chmod 0666 /dev/kvm
-          nproc; free -h; qemu-system-x86_64 --version | head -1
-
       - uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4
 
       - name: Build the ISO
         run: NO_BOOT_OFFER=1 ./bin/omarchy-iso-make
 
+      # The harness runs in an Arch container: Arch's current QEMU and OVMF
+      # (QEMU 11) instead of Ubuntu 24.04's QEMU 8.2, at the paths the
+      # harness expects, the same as on an Omarchy workstation.
       - name: Install unattended, then boot the installed system
-        env:
-          OMARCHY_INTEGRATION_DISK_CACHE: none
-        run: ./test/integration release/*.iso boot --no-preview --memory 8192 --timeout 1800
+        run: |
+          sudo chmod 0666 /dev/kvm
+          docker run --rm --device /dev/kvm -v "$PWD:/w" -w /w \
+            -e OMARCHY_INTEGRATION_DISK_CACHE=none \
+            archlinux:latest bash -euo pipefail -c '
+              pacman -Syu --noconfirm --needed qemu-system-x86 qemu-hw-display-virtio-gpu qemu-hw-display-virtio-vga qemu-img edk2-ovmf socat \
+                imagemagick tesseract tesseract-data-eng mtools dosfstools jq openssh openssl python curl >/dev/null
+              # test/integration installs its tools through Omarchy'"'"'s helper; they are installed above.
+              printf "#!/bin/sh\nexit 0\n" >/usr/local/bin/omarchy-pkg-add
+              chmod 0755 /usr/local/bin/omarchy-pkg-add
+              qemu-system-x86_64 --version | head -1
+              ./test/integration release/*.iso boot --no-preview --memory 8192 --timeout 1800
+            '
 
       - name: Report times
         if: always()