Raise the NPC character budget to 24k and refine the prototype neck

docs/architecture.md

@@ -139,7 +139,7 @@ The runtime NPC contract is intentionally narrow. It is enforced by
 | Core bones | `Head`, `HipL/R`, `KneeL/R`, `ShoulderL/R`, `ElbowL/R`, `HandL/R`, `Spine`, `Neck` at the frozen rest positions. Optional extra bones (fingers, face, toes) are allowed if they do not move the core rest positions or break `NpcAvatar` proxies. |
 | Tint slots | `skin`, `cloth`, `pants`, `accessory`, `hair`; fixed detail materials keep their authored colours. |
 | Orientation | Blender −Y / Godot +Z front, feet grounded near `y = 0`, metre scale. |
-| Budget | 16,000 triangles / 16,000 glTF vertices per character; 1,500 per gear piece; 4,000 per prop. The low-poly `npc_base` remains a fallback, not a second contract. |
+| Budget | 24,000 triangles / 24,000 glTF vertices per character; 1,500 per gear piece; 4,000 per prop. The low-poly `npc_base` remains a fallback, not a second contract. |
 | Textures | 256² albedo + normal + packed ORM per slot; cloth/pants use the 4× `NPC_FABRIC_UV_SCALE` and skip per-character baked AO, while skin/hair/gear keep AO. |
 | Gear attach | Authored in attach-point space: head `Rig/Head` (0, 1.62, 0), back (0, 1.10, 0), chest (0, 1.30, 0), hand (±0.27, 0.78, 0.02); grip 5 cm below the origin. `GEAR_OFFSETS` and `HAND_ITEM_FORWARD` are runtime fit corrections, not authored-geometry changes. |
 | Fallback chain | Library variant → `npc_base.glb` → procedural `NpcAvatar` mesh. Committed GLBs and maps must keep CI offline and Blender-free. |
@@ -217,8 +217,8 @@ GLBs and maps.
 
 | Tool | Role | Committed artifact | Verification gate |
 | --- | --- | --- | --- |
-| `tools/npc_pipeline.py` | Builds the skinned base avatar, five-slot material maps, palette and AI-fabric preparation (`prepare`/`palette`) | `npc_base.glb`, `assets/textures/npc/*_{albedo,normal,orm}.png`, `palette.json` | `audit_glb` against the 16,000-triangle / 16,000-vertex base contract (13 core bones required; extras allowed) |
-| `tools/blender_assets.py` | Builds/renders the library: 8 characters, 18 gear pieces, 20 props, plus `manifest.json`; stdlib `audit`/`fit`/`sheet`/`list` | `assets/models/blender/{npc,npc_gear,props}/*.glb` | Character cap 16,000 tris / 16,000 verts, 1,500 per gear, 4,000 per prop; grounding, UV, degenerate-triangle, attach-fit and manifest coverage checks |
+| `tools/npc_pipeline.py` | Builds the skinned base avatar, five-slot material maps, palette and AI-fabric preparation (`prepare`/`palette`) | `npc_base.glb`, `assets/textures/npc/*_{albedo,normal,orm}.png`, `palette.json` | `audit_glb` against the 24,000-triangle / 24,000-vertex base contract (13 core bones required; extras allowed) |
+| `tools/blender_assets.py` | Builds/renders the library: 8 characters, 18 gear pieces, 20 props, plus `manifest.json`; stdlib `audit`/`fit`/`sheet`/`list` | `assets/models/blender/{npc,npc_gear,props}/*.glb` | Character cap 24,000 tris / 24,000 verts, 1,500 per gear, 4,000 per prop; grounding, UV, degenerate-triangle, attach-fit and manifest coverage checks |
 | `tools/bake_ao.py` | Bakes per-asset AO maps | `<asset>_ao.png` (256²) | Wired through `Materials.apply_ao()`/`SurfaceMaterials`; cloth/pants opt out (see below) |
 | `tools/npc_proportions.py` | Measures exported GLB rest pose (height, head, shoulders, hips, torso, limbs, feet) against the stylized guide | report / JSON in `docs/npc-visual-review.md#proportion-audit` | All eight variants must stay inside the guide after a body change |
 | `tools/npc_baseline.py` | Assembles neutral-baseline sheets and before/after comparisons | `docs/blender_previews/sheet_npc_baseline*.jpg` | Human review against `docs/npc-visual-review.md` |