wip(assembler): M1 round 4 -- cap rebuilt (no hiding), sub-voxel audit, routes + mesh-free queries

Luna, M1 round 4 (resumed after the night stop):
- Cliff: sub-voxel audit (29,929 half-voxel XY columns, min run 3.75 voxels, 0 subvoxel runs;
  old taper control exposes 20,963) and a root-line shelf at the two-voxel minimum.
- Horizon slab = aliased LOD8 cap ceiling. The first fix hid the ceiling at LOD8 (challenged:
  enclosed, interior-lit strates); now the LOD8 cap is rebuilt deterministically from the
  native heightfield, skirts preserved; looking up and out shows the cap present.
- Routes: review manifest with 33 stable-ID route points + capsule/support constraints; capsule
  sweep 0 blocked samples / 0 unsupported centres, negative control detected.
- Server path: World::densityAt answers without render meshes. Physics cooking not available
  standalone.
- Hashes (evaluator + 2,226-tile stream) identical at W1/W8/W16. LOD8: 4.446 s for 529 tiles,
  14.25 M field calls, 165 unknown tiles.
- Captures at 60 fps cap + vsync (owner's GPU coil whine). One cliff probe crossed the ~8 GB
  guard (7.69 GiB) and was stopped before capturing.
My review: cap view matches legacy closely, no slab; native cliff is a clean attached ledge
(cleaner than legacy); a few small spikes on the ridge top.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Standalone/Research/WorldAssemblerM1/round4/world_assembly.json

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