feat: Implement sketch object base class and line geometry

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

src/SketchFeature.h

@@ -2,8 +2,11 @@
 #define SKETCHFEATURE_H
 
 #include <TopoDS_Shape.hxx>
+#include <QList>
 #include "Feature.h"
 
+class SketchObject;
+
 class SketchFeature : public Feature
 {
 public:
@@ -14,6 +17,7 @@ public:
     };
 
     SketchFeature(const QString& name);
+    ~SketchFeature();
 
     QString type() const override;
 
@@ -22,12 +26,16 @@ public:
 
     const TopoDS_Shape& shape() const;
 
+    void addObject(SketchObject* object);
+    const QList<SketchObject*>& objects() const;
+
     void read(const QJsonObject &json) override;
     void write(QJsonObject &json) const override;
 
 private:
     SketchPlane m_plane;
     TopoDS_Shape m_shape;
+    QList<SketchObject*> m_objects;
 };
 
 #endif // SKETCHFEATURE_H