fix(v1.0.1): VDE-016 — using declarations at vde::brep scope, not inside anonymous ns

Root cause: using declarations inside anonymous namespace don't propagate
to public functions defined after the anonymous namespace closes.

Fix:
- using SSICurveData; and using ClassResult; at vde::brep scope
- Remove self-referencing using vde::brep::ClassResult
- Remove duplicate using from inside anonymous namespace

docs/feedback/VDE-016.md

@@ -1,6 +1,6 @@
 ---
 id: VDE-016
-status: open
+status: fixed
 severity: critical
 category: bug
 date: 2026-07-27

src/brep/ssi_boolean.cpp

@@ -41,7 +41,8 @@ using core::AABB3D;
 AABB3D face_bounds(const BrepModel& body, int face_id);
 Vector3D face_normal(const BrepModel& body, int face_id);
 struct SSICurveData;
-using vde::brep::ClassResult;
+using ClassResult;
+using SSICurveData;
 
 /// SSI curve data for a face pair
 struct SSICurveData {
@@ -54,12 +55,9 @@ struct SSICurveData {
 };
 
 namespace {
-// GCC two-phase lookup: bring enclosing namespace types into scope
-using vde::brep::SSICurveData;
-using vde::brep::ClassResult;
 
 // ═══════════════════════════════════════════════════════════
-//  Constants & types
+//  Mesh caching
 // ═══════════════════════════════════════════════════════════
 
 /// ClassResult is now defined in ssi_boolean.h (public API)