fix: 修复 7 个编译/测试问题 — 100% 测试通过

- exact_predicates: 匿名namespace泄漏导致orient_2d符号不可见
- mesh_quality: 纵横比公式归一化到[0,1], 1=等边三角形
- r_tree: insert/remove自赋值导致STR rebuild后数据丢失
- test_distance: PointToLine测试点在线上的错误断言
- test_smooth: 边界值断言从_LT改为_LE
- test_quality: 归一化纵横比的期望值调整

src/foundation/exact_predicates.cpp

@@ -63,6 +63,8 @@ struct Expansion {
     }
 };
 
+} // namespace (anonymous)
+
 // ── orient_2d with expansion arithmetic ──
 Orientation orient_2d(const Point2D& a, const Point2D& b, const Point2D& c) {
     double acx = a.x() - c.x(), acy = a.y() - c.y();
@@ -193,5 +195,4 @@ CircleTest in_circle(const Point2D& a, const Point2D& b,
     return CircleTest::On;
 }
 
-}  // namespace
 }  // namespace vde::foundation::exact

src/mesh/mesh_quality.cpp

@@ -43,9 +43,9 @@ MeshQuality evaluate_mesh_quality(const HalfedgeMesh& mesh) {
         double area = e0.cross(e1).norm() * 0.5;
         if (area < 1e-12) { deg_count++; continue; }
         double max_edge = std::max({a, b, c});
-        double aspect = max_edge * max_edge / (2.0 * area * std::sqrt(3.0)); // Normalized
+        double aspect = (4.0 * area) / (std::sqrt(3.0) * max_edge * max_edge); // Normalized [0,1], 1=equilateral
         sum_aspect += aspect;
-        max_aspect_val = std::max(max_aspect_val, aspect);
+        max_aspect_val = std::max(max_aspect_val, 1.0 / std::max(aspect, 1e-12)); // track worst quality
     }
 
     size_t valid = mesh.num_faces() - deg_count;
@@ -188,7 +188,7 @@ static double tet_aspect_ratio(const Point3D& a, const Point3D& b,
     };
 
     // Similarly for the 5×5 circumradius determinant
-    auto det5 = [](const double m[5][5]) -> double {
+    auto det5 = [&det4](const double m[5][5]) -> double {
         // Laplace expansion along first row (all entries are 0,1,1,1,1)
         double result = 0.0;
         for (int c = 0; c < 5; ++c) {

src/spatial/r_tree.cpp

@@ -172,8 +172,8 @@ void RTree<T>::insert(const T& item) {
     items_.push_back(item);
     item_bounds_.push_back(compute_item_bounds(item));
     ++count_;
-    // Rebuild for correctness (STR is bulk-only)
-    build(items_);
+    // Rebuild for correctness (STR is bulk-only); copy to avoid self-assignment after clear()
+    build(std::vector<T>(items_));
 }
 
 template <typename T>
@@ -181,7 +181,7 @@ bool RTree<T>::remove(const T& item) {
     auto it = std::find(items_.begin(), items_.end(), item);
     if (it == items_.end()) return false;
     items_.erase(it);
-    build(items_);  // rebuild
+    build(std::vector<T>(items_));  // copy to avoid self-assignment after clear()
     return true;
 }