fix: cleanup on empty findmnt + stale profiledef entries

Two pre-existing build.sh bugs surfaced while rebuilding the ISO for
the first time since the April lib/ refactor.

1. safe_cleanup_work_dir runs findmnt | grep | sort in a command
   substitution. When no mounts match (the common case — this is a
   defensive sweep on top of the explicit known-mount loop), grep
   exits 1, pipefail propagates it, set -e exits the script. The
   trap then reports "Build interrupted or failed" and the build
   aborts before doing any work. Swallow the grep status with
   || true; no-match is not an error here.

2. The profiledef.sh file_permissions seds drifted out of sync with
   the lib/ refactor:
   - lib/zfs.sh was removed in 3321f0f but its sed block stayed,
     producing a warning every build ("Cannot change permissions of
     '.../lib/zfs.sh': no such file").
   - lib/raid.sh was added in 19f4624 without a corresponding sed,
     so the file shipped with whatever permissions cp gave it.

   Drop the zfs.sh block and add the raid.sh block.

0 files changed, 0 insertions, 0 deletions