v0.3.1

⛔ DO NOT USE THIS RELEASE

A later adversarial review found live paths in this version that destroy the mesh
you pass it and report success. It is tagged only so the history is complete and
pinnable. Use the latest release.

0.3.0 should not be used. A review of that release found four live paths
that still destroyed data, three of them introduced by 0.3.0's own fixes.

• dissolve_degenerate ran with Blender's hardcoded 1e-4 threshold, in local
  space, entirely independent of mergeDistance. A mesh of 2 mm parts at true
  scale went from 3,042 triangles to zero even with mergeDistance: 0 — and
  the refusal named the one setting that could not fix it. Screws, gems, coins
  and PCB detail all sit inside that default. The threshold is now explicit.
• The zero-geometry refusal fired after the rename. The destination was
  atomically replaced by a husk and the caller was told "The destination is
  unchanged" — a false reassurance, which is worse than no check, because nobody
  re-checks. Measured: 70,492 bytes to 224. The check now runs before the rename.
• Scale is no longer baked into geometry. 0.3.0 applied transform_apply,
  which read the object's own scale and so missed a scale on a parent node —
  92% of a mesh was still destroyed at defaults — and which raised "Cannot apply
  to a multi user" on instanced meshes, turning a working input into a hard
  failure. The world scale is now read and the threshold divided by it: parents
  are included, instancing is untouched, and no geometry is mutated.
• The threshold adjustment applies whether or not cleanGeometry is on. It
  sat inside that branch, so turning welding off silently degraded UV texel
  density by 2.8x on a non-uniformly scaled mesh.
• The receipt's scale counters were provably false for a scale like [-1, 1, 1].
  They now describe the threshold adjustment, which is what actually happens.