Qt6 Migration: Complete migration with DDS/RTI support and build validation

Major Changes:
- Merged latest Qt5 devel content from dlbo (292 files changed, 7 new dirs)
- Consolidated forward-declarations and include folders
- Removed unneeded modules per Niklas' repo check list

Build System Fixes:
- Fixed CMake VERSION_GREATER syntax in ParticipantManagement/CMakeLists.txt
- Added VLC packages (libvlc-dev, vlc-plugin-base) to docker_build.sh
- Added PostgreSQL dev packages (libpq-dev, postgresql-server-dev-all) to Dockerfile
- Fixed locale warnings (ANSI_X3.4-1968 → C.UTF-8)
- Fixed ArcGIS SDK path warnings when BUILD_ARCGIS=OFF

Code Generation Fixes:
- Fixed IDL enum collisions (PortType→CorePortType/DdsutPortType, PdmEventType)
- Fixed Grantlee template svc_translation.cpp.grantlee:
  - Changed {{ idl_enum.name }}_def:: to {{ idl_enum.name }}::
  - Fixed .underlying() calls for C++11 scoped enums (enum class)
- Removed generated files from repo (moc_*, *_dtc.h, *_ftc.h)

Validation:
- BUILD_RTI=ON: SUCCESS
- BUILD_RTI=OFF: SUCCESS
- C++17 standard maintained for RTI 7.7 compatibility
- Ubuntu 26.04 Docker environment verified

Remaining Warnings (expected):
- BgViewer, KDChart, KDReports, Poppler-Qt6 not found (optional features)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt5-before/dlbo/Lts/Viewer/SituationMap/MapImpl/viewshed_impl.h

@@ -0,0 +1,91 @@
+/**
+  * @RDE_HEADER@
+  * Interface-Implementation of Viewshed
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  */
+
+#pragma once
+
+// Own
+#include <Map/viewshed.h> // Interface
+#include "map_impl.h"
+#include "Rubberbands/rubberband_ellipse.h"
+#include "Rubberbands/rubberband_multi_point_feature_3d.h"
+
+
+// Qt
+#include <QPointF>
+
+
+//----------------------------------------------------------------------------
+namespace SituationMap
+{
+
+class ViewshedBase;
+
+class ViewshedImpl : public /*virtual*/ Viewshed
+{
+  using BaseClass = Viewshed;
+
+  public:
+
+    explicit ViewshedImpl(SituationMap::MapImpl *mapImpl);
+    virtual ~ViewshedImpl();
+
+    ViewshedImpl(const ViewshedImpl &other)     = delete;
+    ViewshedImpl &operator=(ViewshedImpl &other) = delete;
+
+    void setViewshedUrl(const QString &viewshedServiceUrl) override;
+
+    bool isReady();
+
+    bool create() override;
+    bool create(double alpha, double innerRadius, double observerHeight, double targetHeight, double beamAngle) override;
+    long create(const ViewshedParameter &viewshedParameter) override;
+  
+    bool modify(long viewshedId, double alpha, double innerRadius, double observerHeight, double targetHeight, double beamAngle) override;
+
+    void remove(long viewshedId = -1) override;
+
+    ViewshedParameter getViewshedParameter(long viewshedId = -1, bool *ok = nullptr) const override;
+
+
+  private Q_SLOTS:
+ 
+    void onRbAbort(RB::RubberbandBase *rbnd);
+    void onRb2DApply(RB::RubberbandBase *rbnd);
+    void onRb3DApply(RB::RubberbandBase *rbnd);
+
+    void onSightFanRb2DApply(RB::RubberbandBase *rbnd);
+    void onSightFanRb3DApply(RB::RubberbandBase *rbnd);
+
+  private:
+
+    ViewshedBase *create_viewshedGP(const ViewshedParameter &viewshedParameter);
+    ViewshedBase *create_viewshedAnalysis(const ViewshedParameter &viewshedParameter);
+
+    void init();
+
+
+    RB::RubberbandEllipse             *createRubberband2D();
+    RB::RubberbandMultiPointFeature3D *createRubberband3D();
+
+    RB::RubberbandEllipse             *createSightFanRubberband2D();
+    RB::RubberbandMultiPointFeature3D *createSightFanRubberband3D();
+
+    LOGGER_T m_logger;      ///< Interface of the Logging-Facility
+
+    class Private;
+    /**
+        * The private d->pointer to not break BC when changing internals of this class
+       */
+    Private *d = nullptr;
+
+}; // ViewshedImpl
+
+
+
+} // namespace SituationMap
+