Derive edge arrow-style icons from cytoscape arrow geometry

[kmcginnes]

Task

The edge arrow-style picker and the edge details panel each had their own set of 11 hand-drawn Arrow* SVG icons (ArrowTriangle, ArrowVee, ArrowCircle, …). These duplicated the arrow-head geometry that EdgePreview/arrowShapes.ts already ports verbatim from cytoscape, so the picker glyphs could drift from what the canvas actually renders.

Replace the 11 icons with a single ArrowStyleIcon that renders the resolved cytoscape geometry for any ArrowStyle, so the picker, edge details, and canvas all draw from one source of truth.

Scope

• Add ArrowStyleIcon (short edge line + arrow head) drawn from resolveArrowGeometry, with a shared viewBox so line thickness/zoom are constant and head trailing edges align across styles; line length varies with head depth.
• Extract ArrowPrimitiveShape as the shared primitive renderer for both the edge preview and the icon.
• Rewire the arrow-style picker (arrowsStyling/EdgeStyleDialog) and EdgeDetail to ArrowStyleIcon.
• Delete the 11 Arrow* icon files and their barrel exports.

Notes

Implemented on branch derive-arrow-icons.

Important

Internal only — this issue is maintained by the core team and is not accepting external contributions.