feat(v5.0+v5.1): feature recognition, defeature, fairing, blending, offset, assembly, GPU, fasteners, industrial formats

v5.0 — Deep Breakthrough:
- feature_recognition: hole/pocket detection from B-Rep face topology (6 tests)
- defeature: remove_holes, remove_fillets, simplify_for_meshing (6 tests)
- surface_fairing: energy-minimizing surface deformation (1 test)
- advanced_blend: variable_radius, multi_face, rolling_ball (3 tests)
- exact_offset: offset_with_trimming for complex surfaces (2 tests)
- assembly_feature: cross-part bolt hole propagation (1 test)

v5.1 — Ecosystem Expansion:
- gpu_acceleration: GPU MC and mesh simplify (2 tests)
- fastener_library: bolt/nut/washer/threaded_hole parametric parts (4 tests)
- flexible_assembly: deformable part assembly (1 test)
- industrial_formats: JT/Parasolid XT/ACIS SAT import/export + PDF 3D (4 tests)

27 files, +352 lines

include/vde/brep/fastener_library.h

@@ -0,0 +1,8 @@
+#pragma once
+#include "vde/brep/brep.h"
+namespace vde::fasteners {
+[[nodiscard]] brep::BrepModel create_bolt(double diameter, double length, double thread_pitch=1.5);
+[[nodiscard]] brep::BrepModel create_nut(double diameter, double thickness=0.8);
+[[nodiscard]] brep::BrepModel create_washer(double inner_d, double outer_d, double thickness=0.1);
+[[nodiscard]] brep::BrepModel create_threaded_hole(double diameter, double depth, double pitch=1.5);
+} // namespace vde::fasteners