Regression test for indoor BSP world-origin fix (Bug B). Verifies that
BSPQuery.FindCollisions with path.StepDown=true and a non-zero
worldOrigin parameter writes a world-space ContactPlane to
CollisionInfo (not a cell-local-space one).
Passes before the call-site fix at TransitionTypes.cs:1442 because
BSPQuery itself is correct when called with the right args — it's the
caller that was passing the defaults. This test locks in the BSPQuery
contract so the relationship between worldOrigin/localToWorld input and
ContactPlane.D output cannot regress silently.
Spec: docs/superpowers/specs/2026-05-20-indoor-bsp-worldorigin-fix-design.md.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>