Derive edge arrow icons from cytoscape arrow geometry

[kmcginnes]

Description

The 11 hand-drawn Arrow* SVG icons (ArrowTriangle, ArrowVee, ArrowCircle, ArrowDiamond, ArrowSquare, ArrowTee, ArrowNone, ArrowTriangleTee, ArrowTriangleCross, ArrowTriangleCircle, ArrowTriangleBackCurve) were a second, hand-maintained copy of geometry that arrowShapes.ts already derives (a verbatim port of cytoscape's arrow shapes). Replaced all 11 with a single ArrowStyleIcon that renders the resolved geometry for any ArrowStyle, so the picker glyphs are guaranteed to match the canvas. The 11 icon files and their barrel exports are deleted.

Supporting: ArrowPrimitiveShape (the polygon/path/circle primitive renderer) is extracted from EdgePreview so it can be shared with ArrowStyleIcon.

How to read

1. ArrowStyleIcon.tsx — the picker/detail icon, drawn from resolveArrowGeometry
2. ArrowPrimitiveShape.tsx — the extracted shared primitive renderer
3. arrowsStyling.tsx — picker rewired to pass ArrowStyle values
4. Deleted components/icons/Arrow*.tsx — the 11 hand-drawn glyphs ArrowStyleIcon replaces

Validation

• pnpm checks passes (types, lint, format); pnpm test passes
• New tests: ArrowStyleIcon.test.tsx — shared viewBox, shaft, per-style head counts, tip-shift math
• Arrow glyphs verified in the running app across the styling picker and edge detail sidebar

Related Issues

• Closes Derive edge arrow-style icons from cytoscape arrow geometry #1985

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I have verified pnpm checks passes with no errors.
• I have verified pnpm test passes with no failures.
• I have covered new added functionality with unit tests if necessary.
• I have updated documentation if necessary.