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/Services/VideoOverlayManagement/handler_infrastructure_data.h

@@ -8,17 +8,20 @@
 
 #pragma once
 
-#include "dds_handler.h"
 #include "logger.h"
 
-#include <InfrastructureManagement/ism_dtc.h>
-
 #include <QtCore/QObject>
 #include <QtCore/QMap>
 
+#if BUILD_RTI
+#include "dds_handler.h"
+#include <InfrastructureManagement/ism_dtc.h>
+#endif
+
 namespace VideoOverlayManagement
 {
 
+#if BUILD_RTI
 class HandlerInfrastructureData : public QObject
 {
   Q_OBJECT
@@ -77,5 +80,19 @@ private: // attributes
 
 
 };
+#else
+// Stub implementation when BUILD_RTI is disabled
+class HandlerInfrastructureData : public QObject
+{
+  Q_OBJECT
+public:
+  explicit HandlerInfrastructureData(QObject *parent = nullptr) : QObject(parent) {}
+  ~HandlerInfrastructureData() = default;
+  bool init(int /*exerciseId*/) { return false; }
+  bool isCameraAvailable(int /*roomId*/) const { return false; }
+  QString getStreamNameFromRoomId(int /*roomId*/) const { return {}; }
+};
+#endif
+
 } // namespace VideoOverlayManagement