Smooth the prototype neck and shrink the shoes

TODO.md

@@ -203,21 +203,24 @@ owner reviews the silhouette and a production integration decision is recorded.
       apply the helper MASK, scale to 1.81 m, retarget the A-pose arms to the contract wrist
       (`x=±0.27`, `z=0.78`), cut the neck at 1.505, decimate, bisect the clothing boundaries, paint
       the five slots, add a short neck flare, project hands, rounded shoe shells, cuffs, the
-      accepted head and the 14-bone armature. Current output: **15,373 tris / 13,552 glTF verts /
-      13,560 seam-split verts / 1.810 m / 14 bones / 10 materials**; `inspect` clean, feet grounded.
+      accepted head and the 14-bone armature. Current output: **15,453 tris / 13,630 glTF verts /
+      13,638 seam-split verts / 1.810 m / 14 bones / 10 materials**; `inspect` clean, feet grounded.
 - [x] Replace the spiky decimated MPFB hands with the project palm/finger primitives, straighten the
       splayed MPFB feet so the shoes point forward, and use rounded shoe shells + cuffs instead of
       flat blocks. Use flat slot colours in the prototype because the one-shot MPFB UV unwrap does
       not match the per-slot NPC atlases.
 - [x] Fix the neck junction without touching the accepted face: cut the decimated neck column
       radially (all-vertex test inside r=0.085) so the shirt shoulder silhouette stays intact,
-      then bridge the opening with a wide 20-segment skin cone from r=0.10 to r=0.056. The lower
-      cone is painted cloth so the opening reads as a V-neck rather than bare chest. No torus,
-      disk shelf, neck brace or sawtooth collar.
-- [x] Seat the ankles in the shoes: remove the lower-leg x-narrowing, raise the shoe shell to
-      0.14 m and add a 0.10 m pant cuff at z=0.13 so the open tapered ankle is hidden.
-- [ ] Owner reviews the updated MPFB body renders (`tmp/npc-parts/mpfb_proto/renders60/`).
-      Remaining known defects: block-shaped shoe silhouette, white shirt hem forms a V at the
+      then bridge the opening with a smooth four-ring lathe neck (r 0.100 → 0.056, 20 segments).
+      The lower rings are painted cloth so the opening reads as a crew neck rather than bare
+      chest. No torus, disk shelf, neck brace or sawtooth collar.
+- [x] Reject destructive vertex smoothing at the neck: a `smooth_vert` pass moved the open body
+      boundary away from the neck cone, opening a dark hole. The lathe gives smooth shading
+      without moving the collar boundary.
+- [x] Shrink the shoes and seat the ankles: shoe shell 0.12 × 0.30 × 0.12 m, sole 0.13 × 0.32 m,
+      shoe centre x=0.17, with a 0.08 m pant cuff (r 0.055/0.061) bridging leg and shoe.
+- [ ] Owner reviews the updated MPFB body renders (`tmp/npc-parts/mpfb_proto/renders63/`).
+      Remaining known defects: shoe toe still reads as a bulb, white shirt hem forms a V at the
       crotch, shirt still reads skin-tight, and the 2k-tri body budget leaves some angular thigh
       facets. These are polish, not blockers for the body direction.
 - [ ] Fix the low-budget seams before any rollout: weld the torso/hip/arm components after the