A character style is a stylesheet rule, direct formatting an inline style on the
run's span. The charStyle mark ranked below TextStyle, so its span sat *inside*
and the rule won over the ancestor's inline style — a 9pt style silently undid a
run's own 10pt. Priority 102 lifts it above TextStyle's 101.
One fixture: 259 → 172 parity issues, lineEnd 49 → 7.
