cockpit/torso: splat3d CPU-render page + muted palette

Adds the second torso page (/torso, the "splat") and softens the colours on
both pages per request.

- /torso (TorsoRender.tsx): a turntable of frames rendered bake-side by
  ndarray::hpc::splat3d (CPU-SIMD EWA, no GPU) over the same torso.splat the
  live page orbits. Drag to scrub, click to pause. A scratchpad torso-render
  driver reads SPL1 -> Gaussian3D -> splat3d turntable (no Inria .ply needed),
  under ndarray's own pinned 1.95 toolchain so q2's workspace stays free of the
  ndarray dependency. 20 JPEG frames (720x960) -> cockpit/public/torso-frames/.
- Muted palette: per-structure golden-angle hue at S=0.34 V=0.78 (was the neon
  S=0.62 V=0.96). torso.splat re-baked; the live three.js page (/torso-live)
  picks it up directly, the splat3d frames re-rendered.
- main.tsx: /torso route; TorsoSplat nav cross-links splat <-> live orbit.

Render verified by viewing the frames: real BodyParts3D torso anatomy, upright,
102 structures in soft pastels. tsc clean. Geometry: BodyParts3D, CC-BY 4.0,
(c) The Database Center for Life Science (attribution shown in-view).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TzqvDqbFRzyx17EkLKBoZF

Author: claude

claude-notes/plans/2026-06-24-fma-torso-bodyparts3d-splat.md

@@ -42,8 +42,19 @@ BodyParts3D (FMA partof tree + FJ OBJ meshes)
 
 ## Checklist
 
-- [ ] `tools/bake_torso_splat.py` — BodyParts3D → SPL1 gaussian asset + manifest
-- [ ] `cockpit/public/torso.splat` (+ `torso.manifest.json` attribution/legend)
-- [ ] SPL1 TS decoder + `/torso-live` three.js orbit page + route
-- [ ] torso.ply + splat3d_flex render → `/torso` frames page + route
-- [ ] attribution surfaced in-UI; verify tsc; commit; PR
+- [x] `tools/bake_torso_splat.py` — BodyParts3D → SPL1 gaussian asset + manifest
+      (231K gaussians, 577 meshes, 102 structures; muted pastel per-structure hues)
+- [x] `cockpit/public/torso.splat` (3.7 MB) + `torso.manifest.json` (attribution/legend)
+- [x] SPL1 TS decoder + `/torso-live` three.js orbit page + route
+- [x] `/torso` splat3d CPU render: scratchpad `torso-render` driver reads SPL1 →
+      `Gaussian3D` → ndarray::hpc::splat3d turntable (no Inria .ply needed) →
+      20 JPEG frames in `cockpit/public/torso-frames/` → `/torso` viewer page + route
+- [x] attribution surfaced in-UI; tsc clean
+- [ ] PR
+
+Notes:
+- The CPU render runs under ndarray's own 1.95 toolchain (scratchpad project,
+  path-dep on ../ndarray) — q2's workspace stays free of the ndarray dep.
+  ~6.6 s/frame on the scalar path (no AVX target-cpu in the scratchpad project);
+  correctness verified by viewing the rendered frames.
+- Colours: golden-angle hue per structure at S=0.34 V=0.78 (muted, per request).