Drop fuse-overlayfs / fuse3 from the apt/dnf install line — the new
mount path is kernel overlayfs via the left4me-overlay helper, no
fuse userspace needed.
Add a one-shot migration block gated by /var/lib/left4me/.kernel-overlay-migrated
that runs before daemon-reload: stop gameservers + web service, force-
unmount any leftover fuse or overlay mounts under runtime/, then wipe
and recreate empty upper/ and work/ for every instance. fuse-overlayfs
running as a non-root user used user.fuseoverlayfs.* xattrs that kernel
overlayfs ignores, so a pre-existing upper/ from the fuse era would
resurrect "deleted" files.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>