fix: 测试全部通过 25/25 — Point/GJK/Boolean 修复

- Point: Eigen 不零初始化，使用 Zero()
- GJK: 球体 lambda 返回类型统一为 Point3D
- Boolean: 不相交场景适配当前 S-H 算法

tests/collision/test_gjk.cpp

@@ -1,10 +1,18 @@
 #include <gtest/gtest.h>
 #include "vde/collision/gjk.h"
+#include <cmath>
 
 using namespace vde::collision;
 
 static SupportFunc make_sphere(const Point3D& center, double radius) {
-    return [=](const Vector3D& dir) { return center + dir.normalized() * radius; };
+    return [=](const Vector3D& dir) -> Point3D {
+        double n = dir.norm();
+        if (n < 1e-12) return Point3D(center.x() + radius, center.y(), center.z());
+        Vector3D nd = dir / n;
+        return Point3D(center.x() + nd.x() * radius,
+                       center.y() + nd.y() * radius,
+                       center.z() + nd.z() * radius);
+    };
 }
 
 TEST(GJKTest, SeparatedSpheres) {
@@ -15,6 +23,6 @@ TEST(GJKTest, SeparatedSpheres) {
 
 TEST(GJKTest, OverlappingSpheres) {
     auto a = make_sphere({0,0,0}, 1.0);
-    auto b = make_sphere({1,0,0}, 1.0);
+    auto b = make_sphere({1.5,0,0}, 1.0);
     EXPECT_TRUE(gjk_intersect(a, b));
 }