fix(editor): bump vtextedit to fix cmark emoji surrogate split

Pulls in vtextedit cd01941: the cmark AST walker was converting cmark's inclusive byte-based end_column with a blind +1, splitting a trailing/adjacent emoji's surrogate pair in styled spans (e.g. headings) into tofu boxes in the markdown editor. Adds a width-aware conversion and regression tests; no golden-master output changes.

Author: tamlok