Phase 0.3-0.5: SVG export + YAML sidecars + asset catalog

- Add hair class KeyMap entries (基髪→BaseHair, 前髪→FrontHair, 胸毛→ChestHair)
- Implement cardinal spline → cubic Bezier SVG export for all 175 body parts
- Generate YAML sidecar files (part.yaml) per part with metadata
- Write Catalog.yaml index for runtime asset loading
- Output to SlaveMatrix/Assets/Parts/{EnglishName}/ structure
- Each part directory contains part.yaml + x{x}y{y}.svg morph variants
- 838 SVGs across 324 morph variants, 175 sidecars, 1 catalog
- Extraction tool now serves as the asset build pipeline step

SlaveMatrix/Assets/Parts/四足膣基/part.yaml

@@ -0,0 +1,11 @@
+id: 四足膣基
+original_key: 四足膣基
+resource: 半身
+morph_x: 1
+morph_y: 1
+variants:
+- x: 0
+  y: 0
+  file: x0y0.svg
+fields:
+- name: 膣基

SlaveMatrix/Assets/Parts/四足膣基/x0y0.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1 1">
+<g transform="translate(0.33734345282867073,0.407103947747691) rotate(0) scale(1,1) translate(-0.03152698640040582,-0.036515748274779464)"><path d="M 0.03605814221841235 0.018701396493113163 C 0.036413580846372896 0.020700895520469956 0.03541465361776517 0.04226205165858537 0.03579224993593238 0.040195625062067065 C 0.03541465361776517 0.04226205165858537 0.030816109144484734 0.04349851565133277 0.031526986400405826 0.04349851565133277 C 0.030816109144484734 0.04349851565133277 0.026884126546712052 0.03812919846554877 0.02726172286487926 0.040195625062067065 C 0.026884126546712052 0.03812919846554877 0.02735126921035985 0.01670189746575638 0.0269958305823993 0.018701396493113174 C 0.02735126921035985 0.01670189746575638 0.032282179036740244 0.016201636733785562 0.03152698640040582 0.016201636733785562 C 0.032282179036740244 0.016201636733785562 0.036413580846372896 0.020700895520469956 0.03605814221841235 0.018701396493113163 Z" fill="#cccccc" stroke="none" stroke-width="0"/>
+</g></svg>