fix(v1.0.1): VDE-011/012/013 — write_stl return bool, StlTrianglef, module options

VDE-011 (Medium): write_stl / write_stl_ascii return bool
- Return false on file open failure, true on success

VDE-012 (Low): StlTrianglef for float precision
- New StlTrianglef struct with Vector3F/Point3F
- to_stl_trianglef() / from_stl_trianglef() conversions

VDE-013 (Medium): Per-module build options
- VDE_BUILD_CURVES/MESH/BREP/SPATIAL/BOOLEAN/COLLISION/SKETCH/SDF/CAPI
- All default ON, parent project can set OFF

src/foundation/io_stl.cpp

@@ -115,8 +115,9 @@ std::vector<StlTriangle> read_stl(const std::string& filepath) {
     return read_stl_binary(filepath);
 }
 
-void write_stl(const std::string& filepath, const std::vector<StlTriangle>& tris) {
+bool write_stl(const std::string& filepath, const std::vector<StlTriangle>& tris) {
     std::ofstream file(filepath, std::ios::binary);
+    if (!file) return false;
     char header[80] = {};
     file.write(header, 80);
     uint32_t count = static_cast<uint32_t>(tris.size());
@@ -129,10 +130,12 @@ void write_stl(const std::string& filepath, const std::vector<StlTriangle>& tris
         uint16_t attr = 0;
         file.write(reinterpret_cast<const char*>(&attr), 2);
     }
+    return true;
 }
 
-void write_stl_ascii(const std::string& filepath, const std::vector<StlTriangle>& tris) {
+bool write_stl_ascii(const std::string& filepath, const std::vector<StlTriangle>& tris) {
     std::ofstream file(filepath);
+    if (!file) return false;
     file.precision(12);
     file << "solid vde\n";
     for (const auto& tri : tris) {
@@ -146,6 +149,14 @@ void write_stl_ascii(const std::string& filepath, const std::vector<StlTriangle>
         file << "  endfacet\n";
     }
     file << "endsolid vde\n";
+    return true;
+}
+
+StlTrianglef to_stl_trianglef(const StlTriangle& t) {
+    return {t.normal.cast<float>(), t.v0.cast<float>(), t.v1.cast<float>(), t.v2.cast<float>()};
+}
+StlTriangle from_stl_trianglef(const StlTrianglef& t) {
+    return {t.normal.cast<double>(), t.v0.cast<double>(), t.v1.cast<double>(), t.v2.cast<double>()};
 }
 
 }  // namespace vde::foundation