feat: Python 绑定 — pybind11 核心/曲线/网格模块

- 使用 pybind11 v2.11.1 (FetchContent) 构建 _vde 原生模块
- 模块化结构: bind_core.cpp / bind_curves.cpp / bind_mesh.cpp
- 暴露核心类型: Point2D, Point3D, Vector3D, AABB3D, Polygon2D
- 暴露曲线: BezierCurve, BSplineCurve, NurbsCurve
- 暴露网格: delaunay_2d/3d, DelaunayResult, HalfedgeMesh
- 变换函数: translate, rotate, scale 等
- Python 包 vde/ 含 __init__.py 及子模块封装
- setup.py 支持 pip install -e . 可编辑安装
- VDE_BUILD_PYTHON CMake 选项 (默认 OFF)，通过 -DVDE_BUILD_PYTHON=ON 启用

python/vde/curves.py

@@ -0,0 +1,17 @@
+"""
+vde.curves — Parametric curves for CAD.
+
+Re-exports from the native _vde.curves submodule:
+    BezierCurve, BSplineCurve, NurbsCurve
+"""
+from vde._vde.curves import (
+    BezierCurve,
+    BSplineCurve,
+    NurbsCurve,
+)
+
+__all__ = [
+    "BezierCurve",
+    "BSplineCurve",
+    "NurbsCurve",
+]