try a different approach to get snap path consistency

the arch snapd wants /var/lib/snapd/snap the snap snapd wants /snap.
link the former to the latter and maybe that will get us going.

we cannot not have /snap because then the snap snapd will error out on
uncreatable /snap. symlinking the other way around also didn't work in
testing.

mkosi.extra/usr/bin/_kdeos-overlay

@@ -37,6 +37,9 @@ mount -v \
 mount -v \
     -o rw,subvol=@root \
     "$rootdisk" "${sysroot}/root"
+mount -v \
+    -o rw,subvol=@snap \
+    "$rootdisk" "${sysroot}/snap"
 mount -v \
     -o rw,subvol=@locale \
     "$rootdisk" "${sysroot}/usr/lib/locale"
@@ -48,8 +51,5 @@ mount -v \
     -t overlay \
     -o "rw,lowerdir=${sysroot}/var,upperdir=${sysroot}/system/@var-overlay/upper,workdir=${sysroot}/system/@var-overlay/work,index=off,metacopy=off" \
     overlay "${sysroot}/var"
-mount -v \
-    -o rw,subvol=@snap \
-    "$rootdisk" "${sysroot}/var/lib/snapd/snap"
 
 # TODO: should we maybe also mount /etc into the initrd /etc so we have early access to fstab and the like

mkosi.postinst.chroot

@@ -7,7 +7,7 @@ set -ex
 env
 
 mkdir --mode 0700 /system # for the kdeos-overlay.service
-ln -s var/lib/snapd/snap /snap # for snapd
+mkdir /snap # for snapd (will get a subvolume mounted into that snapd then mounts the snaps into)
 
 export SYSTEMD_ESP_PATH="$BOOT_MNT"
 mkdir --mode 0700 "$SYSTEMD_ESP_PATH"
@@ -60,12 +60,12 @@ pacman --noconfirm --upgrade /tmp/yay-build/yay/*.pkg.tar.*
 pacman --noconfirm --sync libinih libnsl liburcu lzo python apparmor autoconf-archive go-tools python-docutils squashfs-tools xfsprogs
 # For build deps for systemd-bootchart
 pacman --noconfirm --sync intltool docbook-xsl
-# FIXME: something breaks with snap-confines setuid bit, it doesn't arrive in the final image
 su - builder -c "yay --noconfirm --sync --sudo /bin/true snapd steam-devices-git systemd-bootchart"
 pacman --noconfirm --upgrade /home/builder/.cache/yay/snapd/*.pkg.tar.*
 pacman --noconfirm --upgrade /home/builder/.cache/yay/steam-devices-git/*.pkg.tar.*
 pacman --noconfirm --upgrade /home/builder/.cache/yay/systemd-bootchart/*.pkg.tar.*
 touch /var/lib/snapd/apparmor/snap-confine/.keep # this has been gotten lost in the past for unknown reasons
+ln -s /snap /var/lib/snapd/snap # try to reconcile different default locations for snap mounts by making the arch path a symlink to the canonical one
 userdel --remove builder
 rm /etc/sudoers.d/builder
 rm -rf /home/builder