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/Neck/part.yaml

@@ -0,0 +1,139 @@
+id: Neck
+original_key: 首
+resource: 胴体
+morph_x: 1
+morph_y: 1
+variants:
+- x: 0
+  y: 0
+  file: x0y0.svg
+fields:
+- name: 植性
+- name: 首
+- name: 虫性
+- name: 鱗
+- name: 淫タトゥ
+- name: 悪タトゥ
+- name: ヴィオラ
+- name: 首輪
+joints:
+- position: [
+  -0.004995337548714474,
+  0.0004979414188921913
+]
+- position: [
+  0.016211003027175944,
+  0.000497941418892187
+]
+- position: [
+  -0.0037357220581254146,
+  0.005588012340224058
+]
+- position: [
+  0.014951387536586905,
+  0.005588012340224053
+]
+- position: [
+  0.5,
+  0.4887225994119858
+]
+- position: [
+  0.5,
+  0.5073680233284092
+]
+- position: [
+  0.011869046253740682,
+  0.0028891069362062425
+]
+- position: [
+  0.011869046253740675,
+  0.0028891069362062425
+]
+- position: [
+  0.011869046253740677,
+  0.0034307818046324995
+]
+- position: [
+  0.015058466988291015,
+  0.01001728973385724
+]
+- position: [
+  0.015058466988291015,
+  0.01776672804746955
+]
+- position: [
+  0.015058466988291015,
+  0.017380462313904214
+]
+- position: [
+  0.015058466988291015,
+  0.017049287730588635
+]
+- position: [
+  0.015058466988291015,
+  0.016765346922218434
+]
+- position: [
+  0.015058466988291015,
+  0.01652190317164204
+]
+- position: [
+  -4.469779268346951E-05,
+  0.014092319898051394
+]
+- position: [
+  -0.0014606006442214666,
+  0.014092319898051394
+]
+- position: [
+  0.0070320685144348955,
+  0.01602013802246163
+]
+- position: [
+  0.005616165662896898,
+  0.01602013802246163
+]
+- position: [
+  -0.0020009652566640285,
+  0.002418865533895344
+]
+- position: [
+  -0.003517875083207439,
+  0.010573208435388086
+]
+- position: [
+  0.013216630735125356,
+  0.002418865533895344
+]
+- position: [
+  0.014733540561668867,
+  0.010573208435388086
+]
+- position: [
+  0.008564895603205596,
+  0.011152769902399134
+]
+- position: [
+  0.016686985802775445,
+  0.011152769902399133
+]
+- position: [
+  0.0021093165318941576,
+  0.011152769902399134
+]
+- position: [
+  0.020196223272904115,
+  0.011152769902399133
+]
+- position: [
+  0.004408768010720679,
+  0.007758324996586713
+]
+- position: [
+  0.007521553876108054,
+  0.0077583249965867095
+]
+- position: [
+  0.007995096117065285,
+  0.00775832499658671
+]