Sided twin violins render boxplot whiskers incorrectly

Plotly version: 6.3.0

Follow-up to #1634 (never resolved).

When using sided (split) violins with box=dict(visible=True), the boxplot whiskers are drawn at the inner edge of each half-box, rather than being centered as in a normal boxplot.

This makes the left and right whiskers appear extremely close together, which creates significant visual confusion.

Example from #1634 (Advanced Violin Plot example with box=dict(visible=True)):

My reproduction:

Normal (non-sided) violins for comparison:

Plotly 6.1.2 (in my work):

Possible cause:
The boxplots may be internally split in half to fit each half-violin, shifting the “center” used for whisker rendering to the midpoint between the halves.

Possible solutions:

• Preferred: Render each half-boxplot with whiskers centered over its own half-violin.
• Alternative: Allow configurable spacing between the halves to reduce whisker overlap.

No se especifica ningún archivo fuente ni ninguna prueba. Empieza reproduciendo el ejemplo de sided-violin de Advanced Violin Plot con box=dict(visible=True), y después compáralo con un violin normal y Plotly 6.1.2 mientras rastreas la ruta de renderizado para las cajas divididas. Se considera terminado cuando los bigotes están centrados correctamente para cada mitad sin introducir regresiones en los violines normales.