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/潮吹/x0y2.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(0.3373434528286706,0.2649004817027368) rotate(0) scale(1,1) translate(-0.015396266779668091,-0.015396266779668094)"><path d="M 0.01628218811121558 0.020546792408854375 C 0.016356014888844538 0.0207937984004833 0.016208361333586625 0.02169763797716636 0.01628218811121558 0.02156976624735392 C 0.016208361333586625 0.02169763797716636 0.015248613224410176 0.02208125316660369 0.015396266779668091 0.02208125316660369 C 0.015248613224410176 0.02208125316660369 0.014436518670491637 0.021441894517541478 0.014510345448120595 0.02156976624735392 C 0.014436518670491637 0.021441894517541478 0.014584172225749552 0.02029978641722545 0.014510345448120595 0.020546792408854375 C 0.014584172225749552 0.02029978641722545 0.015543920334926 0.01860569434780679 0.015396266779668084 0.01860569434780679 C 0.015543920334926 0.01860569434780679 0.016356014888844538 0.0207937984004833 0.01628218811121558 0.020546792408854375 Z" fill="#cccccc" stroke="#000000" stroke-width="0.001"/>
+</g></svg>