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.

1 files changed, 5 insertions, 3 deletions

diff --git a/build.sh b/build.sh
index 6144932..06399ec 100755
--- a/build.sh
+++ b/build.sh
@@ -50,9 +50,11 @@ safe_cleanup_work_dir() {
 
         # Catch any other mounts under airootfs (bind mounts not in the
         # explicit list above). Deepest-first via reverse sort.
+        # grep exits 1 on no-match; with pipefail that would propagate and
+        # trip set -e, so swallow it — "no leftover mounts" is the common case.
         local leftover
         leftover=$(findmnt --list --noheadings -o TARGET 2>/dev/null \
-                       | grep "$airootfs" | sort -r)
+                       | grep "$airootfs" | sort -r || true)
         if [[ -n "$leftover" ]]; then
             while IFS= read -r mp; do
                 umount -l "$mp" 2>/dev/null || true
@@ -422,10 +424,10 @@ if grep -q "file_permissions=" "$PROFILE_DIR/profiledef.sh"; then
         /)/ i\  ["/usr/local/bin/lib/disk.sh"]="0:0:755"
     }' "$PROFILE_DIR/profiledef.sh"
     sed -i '/^file_permissions=(/,/)/ {
-        /)/ i\  ["/usr/local/bin/lib/zfs.sh"]="0:0:755"
+        /)/ i\  ["/usr/local/bin/lib/btrfs.sh"]="0:0:755"
     }' "$PROFILE_DIR/profiledef.sh"
     sed -i '/^file_permissions=(/,/)/ {
-        /)/ i\  ["/usr/local/bin/lib/btrfs.sh"]="0:0:755"
+        /)/ i\  ["/usr/local/bin/lib/raid.sh"]="0:0:755"
     }' "$PROFILE_DIR/profiledef.sh"
     sed -i '/^file_permissions=(/,/)/ {
         /)/ i\  ["/etc/shadow"]="0:0:400"