live: mount /system

previously we'd only mount it during calamares run, which is a bit late
since we want to seed flatpaks

mkosi.extra/usr/lib/systemd/system-generators/kde-linux-live-generator

@@ -0,0 +1,41 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+# SPDX-FileCopyrightText: 2024 Harald Sitter <sitter@kde.org>
+
+set -eux
+
+. /usr/lib/os-release
+
+normal_dir=$1
+# shellcheck disable=SC2034
+early_dir=$2
+# shellcheck disable=SC2034
+late_dir=$3
+
+if ! grep "kdeos.live=1" /proc/cmdline; then
+    echo "kdeos.live=1 not in cmdline"
+    exit 1
+fi
+
+if [ "$(readlink --canonicalize /dev/disk/by-label/KDEOSLive)" != "$(readlink --canonicalize /dev/gpt-auto-root)" ]; then
+    echo "gpt-auto-root is not KDEOSLive"
+    exit 1
+fi
+
+cat <<- EOF > "$normal_dir/system.mount"
+# Generated by $(basename "$0")
+[Unit]
+Description=Mount unit for /system
+
+[Mount]
+What=/dev/disk/by-label/KDEOSLive
+Where=/system
+Type=btrfs
+Options=rw,subvol=/
+
+[Install]
+WantedBy=multi-user.target
+EOF
+
+mkdir "$normal_dir/multi-user.target.wants/"
+ln -s ../system.mount "$normal_dir/multi-user.target.wants/system.mount"

mkosi.extra/usr/lib/systemd/system-generators/kdeos-live-generator

@@ -1,15 +0,0 @@
-#!/bin/sh
-# SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
-# SPDX-FileCopyrightText: 2024 Harald Sitter <sitter@kde.org>
-
-if ! /proc/cmdline | grep 'KDEOSLive'; then
-    echo "Not running kdeos-live-generator" > /dev/kmsg
-    exit 0
-fi
-
-ls -lahR /dev/disk > /dev/kmsg
-
-if [ -f /dev/disk/by-label/KDEOSLive ]; then
-    echo "Found by label" > /dev/kmsg
-fi
-