fix(🐛): compare isEdge against the far edges of the rect

[dennytosp]

isEdge is exported from the package root (dom/nodes → datatypes → Rect) and compares the far edges against the rect's width/height rather than x + width / y + height:

pos.x === b.x || pos.y === b.y || pos.x === b.width || pos.y === b.height

It is inconsistent with itself — the near edges are offset by b.x/b.y, the far ones are not. The history explains why: #500 extracted it from an inline check in the Aurora example,

pt.pos.x === 0 || pt.pos.y === 0 ||
pt.pos.x === Math.fround(width) || pt.pos.y === Math.fround(height)

whose rect was always Skia.XYWHRect(0, 0, width, height). At the origin the offset makes no difference, so only half the generalisation was needed and only half got written.

For a rect away from the origin it reports two edges that fall inside the rect and misses the two real ones. For rect(10, 20, 100, 50) the right edge is at x = 110, but the current code answers true for x = 100 and false for x = 110.

Test added to Geometry.spec.ts; it fails on main at the first far-edge assertion.