fix(debian-13-vm): disable systemd-firstboot and add autologin via virt-customize

Newer Debian 13 (Trixie) nocloud images (Jan 29+) have systemd-firstboot
enabled, which blocks the boot process by prompting for timezone and root
password on the serial console. The noVNC console stalls after auditd checks.

Fix by using virt-customize (like docker-vm.sh) to:
- Disable systemd-firstboot.service and mask it
- Pre-seed timezone to Etc/UTC
- Configure autologin on ttyS0 and tty1 for nocloud images
- Set hostname and clear machine-id for unique IDs
- Install libguestfs-tools if not present

Fixes #11807

vm/debian-13-vm.sh

@@ -473,6 +473,17 @@ else
 fi
 msg_ok "Using ${CL}${BL}$STORAGE${CL} ${GN}for Storage Location."
 msg_ok "Virtual Machine ID is ${CL}${BL}$VMID${CL}."
+
+# ==============================================================================
+# PREREQUISITES
+# ==============================================================================
+if ! command -v virt-customize &>/dev/null; then
+  msg_info "Installing libguestfs-tools"
+  apt-get update >/dev/null 2>&1
+  apt-get install -y libguestfs-tools >/dev/null 2>&1
+  msg_ok "Installed libguestfs-tools"
+fi
+
 msg_info "Retrieving the URL for the Debian 13 Qcow2 Disk Image"
 if [ "$CLOUD_INIT" == "yes" ]; then
   URL=https://cloud.debian.org/images/cloud/trixie/latest/debian-13-genericcloud-amd64.qcow2
@@ -486,6 +497,50 @@ echo -en "\e[1A\e[0K"
 FILE=$(basename $URL)
 msg_ok "Downloaded ${CL}${BL}${FILE}${CL}"
 
+# ==============================================================================
+# IMAGE CUSTOMIZATION
+# ==============================================================================
+msg_info "Customizing ${FILE} image"
+
+WORK_FILE=$(mktemp --suffix=.qcow2)
+cp "$FILE" "$WORK_FILE"
+
+# Set hostname
+virt-customize -q -a "$WORK_FILE" --hostname "${HN}" >/dev/null 2>&1
+
+# Prepare for unique machine-id on first boot
+virt-customize -q -a "$WORK_FILE" --run-command "truncate -s 0 /etc/machine-id" >/dev/null 2>&1
+virt-customize -q -a "$WORK_FILE" --run-command "rm -f /var/lib/dbus/machine-id" >/dev/null 2>&1
+
+# Disable systemd-firstboot to prevent interactive prompts blocking the console
+virt-customize -q -a "$WORK_FILE" --run-command "systemctl disable systemd-firstboot.service 2>/dev/null; rm -f /etc/systemd/system/sysinit.target.wants/systemd-firstboot.service; ln -sf /dev/null /etc/systemd/system/systemd-firstboot.service" >/dev/null 2>&1 || true
+
+# Pre-seed firstboot settings so it won't prompt even if triggered
+virt-customize -q -a "$WORK_FILE" --run-command "echo 'Etc/UTC' > /etc/timezone && ln -sf /usr/share/zoneinfo/Etc/UTC /etc/localtime" >/dev/null 2>&1 || true
+virt-customize -q -a "$WORK_FILE" --run-command "touch /etc/locale.conf" >/dev/null 2>&1 || true
+
+if [ "$CLOUD_INIT" == "yes" ]; then
+  # Cloud-Init handles SSH and login
+  virt-customize -q -a "$WORK_FILE" --run-command "sed -i 's/^#*PermitRootLogin.*/PermitRootLogin yes/' /etc/ssh/sshd_config" >/dev/null 2>&1 || true
+  virt-customize -q -a "$WORK_FILE" --run-command "sed -i 's/^#*PasswordAuthentication.*/PasswordAuthentication yes/' /etc/ssh/sshd_config" >/dev/null 2>&1 || true
+else
+  # Configure auto-login on serial console (ttyS0) and virtual console (tty1)
+  virt-customize -q -a "$WORK_FILE" --run-command "mkdir -p /etc/systemd/system/serial-getty@ttyS0.service.d" >/dev/null 2>&1 || true
+  virt-customize -q -a "$WORK_FILE" --run-command 'cat > /etc/systemd/system/serial-getty@ttyS0.service.d/autologin.conf << EOF
+[Service]
+ExecStart=
+ExecStart=-/sbin/agetty --autologin root --noclear %I \$TERM
+EOF' >/dev/null 2>&1 || true
+  virt-customize -q -a "$WORK_FILE" --run-command "mkdir -p /etc/systemd/system/getty@tty1.service.d" >/dev/null 2>&1 || true
+  virt-customize -q -a "$WORK_FILE" --run-command 'cat > /etc/systemd/system/getty@tty1.service.d/autologin.conf << EOF
+[Service]
+ExecStart=
+ExecStart=-/sbin/agetty --autologin root --noclear %I \$TERM
+EOF' >/dev/null 2>&1 || true
+fi
+
+msg_ok "Customized image"
+
 STORAGE_TYPE=$(pvesm status -storage "$STORAGE" | awk 'NR>1 {print $2}')
 case $STORAGE_TYPE in
 nfs | dir)
@@ -512,7 +567,7 @@ msg_info "Creating a Debian 13 VM"
 qm create $VMID -agent 1${MACHINE} -tablet 0 -localtime 1 -bios ovmf${CPU_TYPE} -cores $CORE_COUNT -memory $RAM_SIZE \
   -name $HN -tags community-script -net0 virtio,bridge=$BRG,macaddr=$MAC$VLAN$MTU -onboot 1 -ostype l26 -scsihw virtio-scsi-pci
 pvesm alloc $STORAGE $VMID $DISK0 4M 1>&/dev/null
-qm importdisk $VMID ${FILE} $STORAGE ${DISK_IMPORT:-} 1>&/dev/null
+qm importdisk $VMID ${WORK_FILE} $STORAGE ${DISK_IMPORT:-} 1>&/dev/null
 if [ "$CLOUD_INIT" == "yes" ]; then
   qm set $VMID \
     -efidisk0 ${DISK0_REF}${FORMAT} \
@@ -527,6 +582,10 @@ else
     -boot order=scsi0 \
     -serial0 socket >/dev/null
 fi
+
+# Clean up work file
+rm -f "$WORK_FILE"
+
 DESCRIPTION=$(
   cat <<EOF
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