refactor: Manage active sketch state in ApplicationController

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

src/ApplicationController.cpp

@@ -35,8 +35,14 @@ Document* ApplicationController::document() const
     return m_document;
 }
 
+SketchFeature* ApplicationController::activeSketch() const
+{
+    return m_activeSketch;
+}
+
 void ApplicationController::newDocument()
 {
+    m_activeSketch = nullptr;
     m_document->clear();
     setCurrentFile(QString());
 }
@@ -51,6 +57,7 @@ bool ApplicationController::openDocument()
             return false;
         }
         setCurrentFile(fileName);
+        m_activeSketch = nullptr;
         return true;
     }
     return false;
@@ -93,6 +100,7 @@ void ApplicationController::beginSketchCreation()
                                          "Plane:", items, 0, false, &ok);
     if (ok && !item.isEmpty()) {
         auto feature = new SketchFeature("Sketch");
+        m_activeSketch = feature;
         ViewportWidget::SketchPlane plane;
         if (item == "XY-Plane") {
             plane = ViewportWidget::SketchPlane::XY;
@@ -111,6 +119,7 @@ void ApplicationController::beginSketchCreation()
 
 void ApplicationController::endSketch()
 {
+    m_activeSketch = nullptr;
     emit sketchModeEnded();
 }