v0.16.5

Performance improvements and bug fixes.

Performance

• Substantially faster curve–curve intersection, self-intersection, path
  boolean operations, curve splitting, and projection operations.

API changes

• Added selfIntersection: Intersection? to BezierCurve — a single-result
  convenience alongside the existing selfIntersections array.
• Added public BernsteinPolynomial6/7/8/9 types for higher-degree polynomial
  support.