Fixed:
- office baseline ratio at lineHeight=1 is now (typoAscFrac + winAscFrac) / 2
per font, not a single ratio guess — corrects 0.4.5, which used the font's
own typoAscFrac alone and still missed Roboto by ~4%.
- mode:'office' now shapes (kerns) width measurements by default —
content.width/textBox.width were silently narrower than real PowerPoint
needs for any kerned font, decisive in zero-slack "shrink to fit" boxes.
See CHANGELOG.md [0.4.6] and scripts/office-metrics/RESULTS.md for the full
derivation and oracle data (4-font size/spacing grid, wrap-point corpus).