edentext-fold-marks flag: FoldMarkLayer draws the 87/192mm folds and the
148.5mm punch mark per page inside .paper, so print and PDF include them.
Toggled in the Layout tab. Exported as named EdenFoldMark* lines in the
master page's header (ODF page-relative draw:line, DOCX VML v:line);
both importers read the names back into the flag. Roundtrip Leg 32.