Qt6 Migration: BUILD_RTI guards und CMake fixes

- BUILD_RTI conditional compilation für RTI Connext DDS dependencies
- Namespace fixes in core_dtc.h (Core:: → DDS::Core::)
- CMakeLists.txt: BUILD_RTI option und conditional dependencies
- Handler minelayer: namespace closing mit BUILD_RTI guard
- Build erfolgreich mit BUILD_RTI=OFF validiert

Signed-off-by: Torsten Wierschin <torsten.wierschin@life-maps.com>

qt6-after/qt6-migrated-legatus/Lts/Common/LtsTimelineClassic/TestTimelineModel.h

@@ -8,14 +8,25 @@
 namespace LtsTimelineClassic
 {
 
+class TestTimelineModelTest;
+
 class LTSTIMELINECLASSIC_EXPORT TestTimelineModel : public AbstractTimelineModel
 {
     Q_OBJECT
 
+    friend class TestTimelineModelTest;
+
   public:
     TestTimelineModel();
     void addTestEvent(Event* event);
 
+    // Public wrappers for testing (protected in base class)
+    using AbstractTimelineModel::rowCount;
+    using AbstractTimelineModel::columnCount;
+
+    // Implement pure virtual from AbstractTimelineModel
+    qint64 currentTime() const override { return 0; }
+
   private slots:
     void slotEventAction(EventGraphic*, int);
 };