feat(v6.2): Blender addon + .NET/C# bindings + developer docs + plugin system

v6.2.1 — Blender Integration Addon:
- 5 files, 1,732 lines: __init__, operators (9 ops), panels (4 panels)
- preferences, vde_bridge (subprocess CLI bridge)
- Import/Export STEP, primitives, boolean, SDF→Mesh

v6.2.2 — .NET/C# Bindings (VdeSharp):
- 8 files: NativeMethods (50+ P/Invoke), BrepModel, MeshData, SdfEngine, Assembly
- C API extended with 20 new functions (STEP I/O, Boolean, SDF, Assembly)
- vde_capi rebuilt as SHARED library
- Example: import STEP → boolean → export

v6.2.3 — Developer Docs + Plugin System:
- 7 docs: architecture, contributing, API overview, building, testing, plugin-system
- plugin_system.h/.cpp: PluginInterface, PluginManager, dlopen/LoadLibrary
- README.md updated with v6 features
- Syntax-check passed (GCC 10.2.1, -Wall -Wextra -Wpedantic)

include/vde/capi/vde_capi.h

@@ -588,6 +588,90 @@ VdeMeshHandle vde_body_to_mesh(VdeHandle ctx, VdeBodyHandle body, double deflect
  */
 void vde_body_free(VdeBodyHandle body);
 
+/** @brief 深拷贝 B-Rep 实体 */
+VdeBodyHandle vde_body_clone(VdeHandle ctx, VdeBodyHandle body);
+
+// ── B-Rep STEP/IGES I/O ──
+
+/** @brief 从 STEP 文件导入 B-Rep 实体列表。返回数量，每个 body 写入 out_bodies */
+int vde_body_load_step(VdeHandle ctx, const char* path, VdeBodyHandle** out_bodies);
+
+/** @brief 从 IGES 文件导入 B-Rep 实体列表 */
+int vde_body_load_iges(VdeHandle ctx, const char* path, VdeBodyHandle** out_bodies);
+
+/** @brief 将 B-Rep 实体列表导出为 STEP 文件。成功返回 1 */
+int vde_body_save_step(VdeHandle ctx, VdeBodyHandle* bodies, int count, const char* path);
+
+/** @brief 将 B-Rep 实体列表导出为 IGES 文件 */
+int vde_body_save_iges(VdeHandle ctx, VdeBodyHandle* bodies, int count, const char* path);
+
+// ── B-Rep Boolean ──
+
+/** @brief B-Rep 布尔运算。op: 0=Union, 1=Intersection, 2=Difference (A\B) */
+VdeBodyHandle vde_body_boolean(VdeHandle ctx, VdeBodyHandle a, VdeBodyHandle b, int op);
+
+// ── Mesh face data access ──
+
+/** @brief 获取网格面的顶点索引。返回顶点数，out_indices 需调用 vde_free_buffer 释放 */
+int vde_mesh_get_face(VdeMeshHandle mesh, size_t face_idx, int** out_indices);
+
+// ═══════════════════════════════════════════════════════════
+//  SDF 建模
+// ═══════════════════════════════════════════════════════════
+
+/** @brief SDF 节点句柄（不透明） */
+#ifndef VDE_SDF_HANDLE_DEFINED
+typedef struct VdeSdfNode* VdeSdfHandle;
+#endif
+
+/** @brief 创建 SDF 球体节点 */
+VdeSdfHandle vde_sdf_sphere(VdeHandle ctx, double radius);
+
+/** @brief 创建 SDF 盒子节点 */
+VdeSdfHandle vde_sdf_box(VdeHandle ctx, double hx, double hy, double hz);
+
+/** @brief 创建 SDF 圆柱节点 */
+VdeSdfHandle vde_sdf_cylinder(VdeHandle ctx, double radius, double height);
+
+/** @brief SDF 布尔并集 */
+VdeSdfHandle vde_sdf_union(VdeHandle ctx, VdeSdfHandle a, VdeSdfHandle b);
+
+/** @brief SDF 布尔交集 */
+VdeSdfHandle vde_sdf_intersection(VdeHandle ctx, VdeSdfHandle a, VdeSdfHandle b);
+
+/** @brief SDF 布尔差集 */
+VdeSdfHandle vde_sdf_difference(VdeHandle ctx, VdeSdfHandle a, VdeSdfHandle b);
+
+/** @brief SDF 转网格 */
+VdeMeshHandle vde_sdf_to_mesh(VdeHandle ctx, VdeSdfHandle sdf, int resolution);
+
+/** @brief 释放 SDF 节点 */
+void vde_sdf_free(VdeSdfHandle sdf);
+
+// ═══════════════════════════════════════════════════════════
+//  装配体
+// ═══════════════════════════════════════════════════════════
+
+/** @brief 装配体句柄 */
+#ifndef VDE_ASSEMBLY_HANDLE_DEFINED
+typedef struct VdeAssembly* VdeAssemblyHandle;
+#endif
+
+/** @brief 创建装配体 */
+VdeAssemblyHandle vde_assembly_create(VdeHandle ctx, const char* name);
+
+/** @brief 向装配体根节点添加零件 */
+int vde_assembly_add_part(VdeAssemblyHandle assembly, const char* name, VdeBodyHandle body);
+
+/** @brief 获取装配体零件数量 */
+int vde_assembly_part_count(VdeAssemblyHandle assembly);
+
+/** @brief 释放装配体（不释放其中的 body，调用方自行管理） */
+void vde_assembly_free(VdeAssemblyHandle assembly);
+
+/** @brief 释放 body 句柄数组（由 load_step/load_iges 返回） */
+void vde_body_free_array(VdeBodyHandle* bodies, int count);
+
 // ═══════════════════════════════════════════════════════════
 //  序列化
 // ═══════════════════════════════════════════════════════════