fix: format_utils rename fmt→format_fn, iges_import insert_or_assign

src/brep/iges_import.cpp

@@ -582,7 +582,7 @@ private:
         if (!ent) {
             // Return default line
             auto nc = curves::NurbsCurve({Point3D(0,0,0), Point3D(1,0,0)}, {0,0,1,1}, {1,1}, 1);
-            curve_cache_[de_index] = nc;
+            curve_cache_.insert_or_assign(de_index, nc);
             return nc;
         }
 
@@ -600,7 +600,7 @@ private:
         } catch (const std::exception&) {
             // Keep default line on error
         }
-        curve_cache_[de_index] = nc;
+        curve_cache_.insert_or_assign(de_index, nc);
         return nc;
     }
 
@@ -850,7 +850,7 @@ private:
             std::vector<std::vector<Point3D>> g = {{Point3D(0,0,0), Point3D(1,0,0)},
                                                     {Point3D(0,1,0), Point3D(1,1,0)}};
             auto ns = curves::NurbsSurface(g, {0,0,1,1}, {0,0,1,1}, {}, 1, 1);
-            surface_cache_[de_index] = ns;
+            surface_cache_.insert_or_assign(de_index, ns);
             return ns;
         }
 
@@ -877,7 +877,7 @@ private:
             // Keep default surface
         }
 
-        surface_cache_[de_index] = ns;
+        surface_cache_.insert_or_assign(de_index, ns);
         return ns;
     }