Dynamic and articulations must not be duplicated onto a bar-crossing tie's second half

A tied note that crosses a bar line is one sustained sound; the dynamic and any articulation belong to the note's single onset (the first half) — the tied continuation carries neither.

A public-API request authors a single note `{ pitch: "C5", duration: "h.", dynamic: "f", articulations: ["accent"] }` that spans a bar line the auto-splitter must break into two tied notes; both resulting `ScoreNote`s print "f" and both carry the accent wedge, doubling both marks over one sustained pitch.

Gould, Behind Bars, ch. Articulation and ch. Dynamics — marks of attack (accent, staccato, tenuto, marcato) and dynamic labels attach to the onset, never to a tied continuation, which has no re-attack.

This rule can be decided from pitches, durations and voices — no layout required. A validator can check it before anything is drawn.