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/羽根箒/part.yaml

@@ -0,0 +1,50 @@
+id: 羽根箒
+original_key: 羽根箒
+resource: カーソル
+morph_x: 1
+morph_y: 1
+variants:
+- x: 0
+  y: 0
+  file: x0y0.svg
+fields:
+- name: 羽根1
+- name: 羽根2
+- name: 羽根3
+- name: 羽根4
+- name: 羽根5
+- name: 羽根
+- name: 柄
+joints:
+- position: [
+  0.2630468763449424,
+  0.29353895764985083
+]
+- position: [
+  0.2645048960227844,
+  0.2444700333174513
+]
+- position: [
+  0.2598452193677602,
+  0.25113386943765986
+]
+- position: [
+  0.2555697159233386,
+  0.25554641846963594
+]
+- position: [
+  0.252280345465558,
+  0.26005648940840986
+]
+- position: [
+  0.249928475267765,
+  0.2643595320473664
+]
+- position: [
+  0.009302710415341274,
+  0.0007441923450368609
+]
+- position: [
+  0.009302710415341272,
+  0.009302710415341276
+]