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/CMakeLists.txt

@@ -1,12 +1,27 @@
-option(VDE_BUILD_PYTHON "Build Python bindings" OFF)
+cmake_minimum_required(VERSION 3.16)
 
-if(VDE_BUILD_PYTHON)
-    find_package(pybind11 REQUIRED)
-    message(STATUS "Building Python bindings for ViewDesignEngine")
+# ── Fetch pybind11 ──────────────────────────────────
+include(FetchContent)
+FetchContent_Declare(
+    pybind11
+    URL https://github.com/pybind/pybind11/archive/refs/tags/v2.11.1.tar.gz
+    URL_HASH SHA256=d475978da0cdc2d43dd73e309f0f53263607dd08f31d5facb02c8110e4a1ebd8
+)
+FetchContent_MakeAvailable(pybind11)
 
-    pybind11_add_module(_vde
-        bindings.cpp
-    )
-    target_link_libraries(_vde PRIVATE vde)
-    target_compile_definitions(_vde PRIVATE VDE_BUILDING_PYTHON)
-endif()
+# ── _vde native module ─────────────────────────────
+pybind11_add_module(_vde
+    src/bind_module.cpp
+    src/bind_core.cpp
+    src/bind_curves.cpp
+    src/bind_mesh.cpp
+)
+
+target_include_directories(_vde
+    PRIVATE ${CMAKE_SOURCE_DIR}/include
+)
+
+target_link_libraries(_vde PRIVATE vde)
+
+# Python 3.8+ compatibility
+target_compile_features(_vde PRIVATE cxx_std_17)