Sync lab-seeds to /shared/cluster in sync-cluster-scripts.

Ensures composed backend overlays include media pipeline PHP/API/JS after
ac-deploy updates.

Co-authored-by: Cursor <cursoragent@cursor.com>

sim/cluster0/scripts/sync-cluster-scripts.sh

@@ -6,6 +6,9 @@ DST="${2:-/shared/cluster}"
 [ -d "$SRC/scripts" ] || { echo "missing $SRC"; exit 1; }
 cp -a "$SRC/scripts/." "$DST/scripts/"
 cp -a "$SRC/nginx/." "$DST/nginx/"
+if [ -d "$SRC/lab-seeds" ]; then
+  cp -a "$SRC/lab-seeds/." "$DST/lab-seeds/"
+fi
 install -m644 "$SRC/cluster.env" "$DST/cluster.env"
 install -m755 "$SRC/populate_lab_setup.sh" "$DST/"
 install -m755 "$SRC/verify_lab_setup.sh" "$DST/" 2>/dev/null || true