forked from 1b-agent/opencadstudio-upstream
The preview box rendered a hardcoded `text("AaBbCc 0123")` that ignored
every edited property. Replace it with a canvas that tessellates the
sample string through the same stroke path the text entities use
(`lff::tessellate_text_ex`), so font, width factor, oblique angle and the
backward/upside-down flags are reflected live as fields change. Effective
font follows the entity rule (TrueType name wins, else stroke font file);
the result is fit to the preview box with Y flipped.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>