Three built-in scenes declare kind: mesh with no mesh field

[flyingrobots]

neon-orbit.jedit-scene, mirror-hall.jedit-scene and aurora-vault.jedit-scene cannot be opened from the scene picker. Each fails with:

scene.objects[0].mesh must be one of 'bunny', 'dragon', or 'teapot'.

Cause

Their first object declares "kind": "mesh" but carries no mesh field at all:

{
  "kind": "mesh",
  "radius": 1.45,
  "footprintRadius": 1.45,
  "height": 2.35,
  "color": [224, 113, 63],
  "reflectivity": 0.22
}

Not the on-demand loading bug

Worth stating explicitly, because it looks similar: this is not the empty-mesh-library problem fixed in #321. These three fail identically against a fully loaded library — verified by calling loadBuiltInTitleScene with loadStartupTitleMeshes():

OK   continuum-gate   OK   bunny         OK   neon-dispersion
OK   teapot-cornell   OK   teapot-gallery
FAIL neon-orbit       FAIL mirror-hall   FAIL aurora-vault
OK   eclipse-gate     OK   prism-garden  OK   ember-court
OK   material-lab     OK   sphere        OK   column
OK   sphere-ground

12 of 15 decode. These 3 are a defect in the scene data.

Fix

Either give each object a valid mesh id, or change kind to whatever primitive the geometry fields actually describe — radius/height/footprintRadius suggest these were meant to be capsules or cylinders rather than meshes.

spec/scene-picker-mesh-loading.spec.mjs asserts specifically that no scene fails for want of an unloaded mesh, so it stays green while these remain broken and will not mask a future loading regression.