Prepare the head-prototype owner sign-off sheet (before/after at 1.85m)

docs/3d-model-review.md

@@ -244,7 +244,9 @@ front/three-quarter/profile and judged side by side:
 | s64 | 2,470 / 4,768 | visually identical to s48 | indistinguishable from s48 | reject (wasted verts) |
 
 The chosen s48 is the `head_proto` default; the rejected s24/s64 stay local under
-`tmp/npc-parts/`.
+`tmp/npc-parts/`. A before/after sign-off sheet (current `_face` vs s48, 1.85 m
+front/three-quarter/profile) is
+[`blender_previews/sheet_head_proto_before_after.jpg`](blender_previews/sheet_head_proto_before_after.jpg).
 
 ## Scorecard skeleton