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/射精/part.yaml

@@ -0,0 +1,79 @@
+id: 射精
+original_key: 射精
+resource: カーソル
+morph_x: 2
+morph_y: 7
+variants:
+- x: 0
+  y: 0
+  file: x0y0.svg
+- x: 0
+  y: 1
+  file: x0y1.svg
+- x: 0
+  y: 2
+  file: x0y2.svg
+- x: 0
+  y: 3
+  file: x0y3.svg
+- x: 0
+  y: 4
+  file: x0y4.svg
+- x: 0
+  y: 5
+  file: x0y5.svg
+- x: 0
+  y: 6
+  file: x0y6.svg
+- x: 1
+  y: 0
+  file: x1y0.svg
+- x: 1
+  y: 1
+  file: x1y1.svg
+- x: 1
+  y: 2
+  file: x1y2.svg
+- x: 1
+  y: 3
+  file: x1y3.svg
+- x: 1
+  y: 4
+  file: x1y4.svg
+- x: 1
+  y: 5
+  file: x1y5.svg
+- x: 1
+  y: 6
+  file: x1y6.svg
+- x: 1
+  y: 7
+  file: x1y7.svg
+- x: 1
+  y: 8
+  file: x1y8.svg
+- x: 1
+  y: 9
+  file: x1y9.svg
+- x: 1
+  y: 10
+  file: x1y10.svg
+- x: 1
+  y: 11
+  file: x1y11.svg
+- x: 1
+  y: 12
+  file: x1y12.svg
+- x: 1
+  y: 13
+  file: x1y13.svg
+- x: 1
+  y: 14
+  file: x1y14.svg
+fields:
+- name: 精液
+joints:
+- position: [
+  0.133501349118799,
+  0.15866835892351938
+]