standablePointNear could push an agent's cone out of wall ink but never
pull it back onto the painted floor: the pull reused the push-out helper
with a negated clearance, and that helper always lands on the outside of
whatever rings it is given, so the retry returned the same outside point
and the cone hid whenever the agent's centre sat just off the floor
edge. One helper now steps across the nearest edge to whichever side the
caller wants, and a test covers all three cases.

SvgHeightNative.close threw on a refused native close before detaching
the finalizer or marking itself closed, so a dispose could escape with a
half-closed handle and skip the other side's teardown. It now marks
itself closed and leaves the handle with the finalizer.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>