Right-alignment fix (color-emoji measurement)
Right-aligned text no longer drifts left when a color-emoji face is supplied. measureWidthPt's emoji-aware path rounded each glyph's advance to points before summing, over-counting a contiguous run by up to ~0.5pt per glyph versus what is actually drawn (one run, rounded once). The alignment offset then shifted the line left — a 15-digit tabular number drifted ~3pt. It now accumulates font units and rounds once per contiguous text run, matching the rendered width. Callers that pass no emoji font were never affected.
@Preview glyph positions — the live preview bridge placed each glyph at a running sum of per-glyph rounded advances, so digit-heavy right-aligned runs ran past their edge on screen (the exported PDF was always correct). Glyphs now sit at the round-once cumulative x, so a run ends exactly at its measured width.
Trailing-whitespace trim — each wrapped line is trimmed so an invisible trailing tab / non-breaking space can't shift right- or centre-aligned text.
Golden PDF output is unchanged for the no-emoji path.