BOS opts in to bakery's system prefix so desktop apps live on @
and ride snapper/grub-btrfs snapshots. The builder home stays
~/.local; build-local.sh copies bins, share/data, and user units
onto the image. Per-user installed.json and the index cache stay
in skel. Recovery is still grub-btrfs, not snapper rollback.
Snapshots panel was non-functional (wrong snapper flag); breadgreet picked
the wrong session .desktop and skipped bos-session's PATH fixup; Calamares
aborted offline installs over an unnecessary packages module; snapshot
rollback silently no-op'd on BOS's pinned-subvolume layout (now points at
grub-btrfs instead); breadcrumbs was configurable but had no daemon to run
it. Also: SUPER+I double-bind, breadpaper/packages panels blocking the GTK
main thread, dead polkit rule, and a sweep of smaller drift (default
sidebar view, stale wording, missing .desktop launchers, wallpaper daemon
not recording its own default).
