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/Map/overlay_handler.h

@@ -0,0 +1,95 @@
+/**
+  * @RDE_HEADER@
+  * Interface of AbstractMapObject
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  */
+
+#pragma once
+
+
+// Own
+#include "situation_map_export.h"
+
+
+// Qt
+#include <QMap>
+
+
+//----------------------------------------------------------------------------
+namespace SituationMap
+{
+class Map;
+
+/**
+ * @brief The OverlayHandler class handles overlays produced by the PlanEditor.
+ */
+class SITUATIONMAP_EXPORT OverlayHandler
+{
+
+public:
+  OverlayHandler()          = default;   ///< Contructor
+  virtual ~OverlayHandler() = default;   ///< Destructor
+
+  static OverlayHandler *create(Map *map);
+
+  /*! \name Adding / Updating */
+  //@{
+  /**
+  * @brief Add an Overlay.
+  * @param key to associate the overlay with. Should not be less than 0.
+  * @param name to use (displayname)
+  * @param overlayContent to insert.
+  * @param isSnapshot to ensure correct layer order.
+  * @return True on success, otherwise false.
+  */
+  virtual bool setOverlay(int key, const QString &name, const QByteArray &overlayContent, bool isSnapshot = false) = 0;
+
+  virtual QByteArray content(int key) const = 0;
+
+  virtual double minScale(int key) const = 0;
+  virtual bool   setMinScale(int key, double minScale) = 0;
+
+  virtual double maxScale(int key) const = 0;
+  virtual bool   setMaxScale(int key, double maxScale) = 0;
+
+  virtual double opacity(int key) const = 0;
+  virtual bool   setOpacity(int key, double opacity) = 0;
+  //@}
+
+  virtual bool reorderOverlays(const QVector<int> &orderOfIds) = 0;
+
+  /*! \name Visibility */
+  //@{
+  virtual bool setOverlayVisibility(int key, bool visibility) = 0;
+  virtual bool overlayVisibility(int key) const = 0;
+  //@}
+
+  /*! \name Removing */
+  //@{
+  /**
+   * @brief Remove an Overlay
+   * @param key to be remove()
+  * @return True on success, otherwise false.
+   */
+  virtual bool removeOverlay(int key) = 0;
+
+  virtual int removeAllOverlays() = 0;
+  //@}
+
+
+  /*! \name Retrieving */
+  //@{
+  virtual int         overlayCount() const = 0;
+  virtual QList<int>  overlays() const = 0;
+  virtual bool        containsOverlay(int key) const = 0;
+//  QString        getOverlay(int key);
+  //@}
+
+
+};
+
+
+} // namespace SituationMap
+