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/LtsWidgets/lts_abstract_table_model.h

@@ -84,7 +84,7 @@ public:
     if (row < 0 || row >= m_vecData.size())
       return false;
 
-    int range = std::min(row + count, m_vecData.size());
+    int range = std::min(row + count, static_cast<int>(m_vecData.size()));
 
     beginRemoveRows(QModelIndex(), row, range - 1);
     m_vecData.erase(m_vecData.begin() + row, m_vecData.begin() + range);