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/流血中/part.yaml

@@ -0,0 +1,74 @@
+id: 流血中
+original_key: 流血中
+resource: その他
+morph_x: 1
+morph_y: 5
+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
+fields:
+- name: 血痕
+- name: 流血1
+- name: 流血2
+joints:
+- position: [
+  0.3798670310818434,
+  0.3946808427924712
+]
+- position: [
+  0.38857437113558735,
+  0.3918516565072121
+]
+- position: [
+  0.09500000000000003,
+  0.07832546419974121
+]
+- position: [
+  0.09500000000000003,
+  0.09579103261284956
+]
+- position: [
+  0.09500000000000003,
+  0.080019224415653
+]
+- position: [
+  0.09500000000000003,
+  0.09930558506086655
+]
+- position: [
+  0.09500000000000003,
+  0.08171298463156479
+]
+- position: [
+  0.09500000000000003,
+  0.10282013750888354
+]
+- position: [
+  0.09500000000000003,
+  0.08340674484747657
+]
+- position: [
+  0.09500000000000003,
+  0.10633468995690053
+]
+- position: [
+  0.09500000000000003,
+  0.08510050506338836
+]
+- position: [
+  0.09500000000000003,
+  0.10984924240491752
+]