feat: implement type-safe ReferenceProperty for SmartPointer fields and add UI support for object selection via context-aware dropdowns

app/gcompose/src/MainPanel.cpp

@@ -127,7 +127,10 @@ MainPanel::MainPanel(QWidget* parent) : QWidget(parent), m_context(nullptr), m_m
 void MainPanel::setContext(uLib::ObjectsContext* context) {
     m_context = context;
     m_contextPanel->setContext(context);
-
+    
+    // Propagate context to all panels for reference property dropdowns
+    m_contextPanel->setPropertyContext(context);
+    m_firstPane->setContext(context);
     if (m_mainVtkContext) {
         if (auto* viewport = qobject_cast<uLib::Vtk::QViewport*>(m_firstPane->currentViewport())) {
             viewport->RemoveProp3D(*m_mainVtkContext);