feat: Implement sketch object base class and line geometry

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

src/SketchFeature.cpp

@@ -1,10 +1,19 @@
 #include "SketchFeature.h"
+#include "SketchObject.h"
+#include "SketchLine.h"
+
+#include <QJsonArray>
 
 SketchFeature::SketchFeature(const QString& name)
     : Feature(name)
 {
 }
 
+SketchFeature::~SketchFeature()
+{
+    qDeleteAll(m_objects);
+}
+
 QString SketchFeature::type() const
 {
     return "Sketch";
@@ -25,6 +34,16 @@ const TopoDS_Shape& SketchFeature::shape() const
     return m_shape;
 }
 
+void SketchFeature::addObject(SketchObject* object)
+{
+    m_objects.append(object);
+}
+
+const QList<SketchObject*>& SketchFeature::objects() const
+{
+    return m_objects;
+}
+
 void SketchFeature::read(const QJsonObject& json)
 {
     Feature::read(json);
@@ -34,6 +53,23 @@ void SketchFeature::read(const QJsonObject& json)
         else if (planeStr == "XZ") m_plane = SketchPlane::XZ;
         else if (planeStr == "YZ") m_plane = SketchPlane::YZ;
     }
+
+    if (json.contains("objects") && json["objects"].isArray()) {
+        QJsonArray objectsArray = json["objects"].toArray();
+        qDeleteAll(m_objects);
+        m_objects.clear();
+        for (const QJsonValue& value : objectsArray) {
+            QJsonObject objectJson = value.toObject();
+            if (objectJson.contains("type") && objectJson["type"].isString()) {
+                QString type = objectJson["type"].toString();
+                if (type == "Line") {
+                    auto line = new SketchLine();
+                    line->read(objectJson);
+                    m_objects.append(line);
+                }
+            }
+        }
+    }
 }
 
 void SketchFeature::write(QJsonObject& json) const
@@ -46,4 +82,12 @@ void SketchFeature::write(QJsonObject& json) const
         case SketchPlane::YZ: planeStr = "YZ"; break;
     }
     json["plane"] = planeStr;
+
+    QJsonArray objectsArray;
+    for (const auto& object : m_objects) {
+        QJsonObject objectJson;
+        object->write(objectJson);
+        objectsArray.append(objectJson);
+    }
+    json["objects"] = objectsArray;
 }