fix: clip_mesh 改用 brute-force inside test (BVH 射线有容差 bug)

src/boolean/boolean_mesh.cpp

@@ -138,7 +138,8 @@ HalfedgeMesh clip_mesh(const HalfedgeMesh& a, const HalfedgeMesh& b,
         core::Point3D v2 = a.vertex(vis[2]);
         core::Point3D centroid = (v0 + v1 + v2) * (1.0 / 3.0);
 
-        bool inside = is_point_inside_bvh(centroid, bvh_b);
+        // Use brute-force check for correct results (BVH ray query has epsilon issues)
+        bool inside = is_point_inside_mesh(centroid, b);
         if (invert_b) inside = !inside;
 
         // Keep the face if its centroid is OUTSIDE (b)