Articulation on a slurred (but not tied) note is always valid — do not conflate slur with tie

A slur connects notes into one smooth phrase for BOWING/BREATH purposes, but each note under a slur is still its own attack (a different pitch, or the same pitch re-struck) and may carry its own staccato/accent/tenuto exactly as an unslurred note would — this is the standard "slurred staccato" figure (soft, separated notes in one bow/breath), a distinct and legitimate combination from portato. This is the OPPOSITE convention from a tie (expr-artic-tied-continuation), where the destination note genuinely has no new attack.

An automated check incorrectly implemented as "no articulation under any curve/arc modifier" would wrongly flag a completely ordinary slurred-staccato passage (e.g. a Fux second-species exercise where each note of a two-note slur carries a staccato dot) as an error, because it failed to distinguish a `slurStart`/`slurEnd` pair from a `tie`/`tiedToNext` pair.

Gould, Behind Bars, ch. Slurs and ch. Articulation — slurred staccato ("louré"/"portato-under-slur" in string terminology) is shown explicitly as standard notation, distinct from an unmarked legato slur; Ross, The Art of Music Engraving, gives the same figure under bowing conventions.

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