FX.39 MarkupCraft: add a stamp or signature from an image file, not only by paste

Reported 2026-10-25 (0.7): there is a way to paste a stamp or signature image but not to pick one from a folder, and no flatten option; also asked how to use a scanned code book. Untested.

Checked 2026-11-05 by markup-fix-09: already built in 0.7.1 (71.7 Insert a picture from a file, 71.8 signature from a file) and in the released 0.8.1. Stamp tool > Picture or My signature (file picker, scan made see-through, list of saved signatures in this browser), Edit > More > Insert a picture from a file, Flatten into the page when saved in Properties; a picture can also be saved as a stamp in the tool chest. Tested browser-071.mjs 39/0 and test-markupcraft 565/0. Help: stamps-and-notes. Scanned code book: not asked of the reporter; a scanned page opens as a PDF page like any other.