v0.9.1 — Transverse crossing fix

Patch release for a correctness fix in axiolid-measure.

mesh_distance and proximity_components reported a nonzero separation for two meshes whose triangles genuinely interpenetrate, contradicting the documented contract that crossing surfaces report zero. The pairwise scan sampled vertex/triangle and edge/edge candidates only; a transverse crossing is realised where an edge passes through a face, so every family missed it.

Fail-open for clash detection: a real interpenetration was indistinguishable from a real gap. Coplanar overlap was already handled, which is why existing tests did not catch it.

Fixes #91.