Activates the per-box loop landed in the prior commit. SO External
reads line.product_uom_qty; Job External reads job.qty. Inner
template now renders one sticker per physical box, marking each
with "X / N" in the Qty row.
Verified on fp.job 2635 (qty temporarily set to 3): 3-page PDF
with Qty rows "1 / 3", "2 / 3", "3 / 3" — each page identical
otherwise (same WO#, same QR, same body fields).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
974b8a5152