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/Services/AudioVideoManagement/handler_menu_struct.h

@@ -0,0 +1,83 @@
+/**
+  * @RDE_HEADER@
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  */
+#pragma once
+
+#include "logger.h"
+#include <AudioVideoManagement/avm_fts.h>
+#include <AudioVideoManagement/avm_db.h>
+#include <QObject>
+#include <QMap>
+#include <QList>
+
+namespace AudioVideoManagement
+{
+
+namespace Interface
+{
+class Dts;
+}
+
+class ObjectMenuStruct;
+class AvMenuStruct;
+
+/**
+ * cfroebel 2018-03-14:
+ * As of now HandlerMenuStruct only handles manually created Video- and
+ * AnnouncementMenus.
+ * There are also default menus (Video and Announcement) for each exercise;
+ * but those are now handeled by DefaultAvMenus.
+ *
+ * @see DefaultAvMenus.
+ */
+class HandlerMenuStruct :
+  public QObject,
+  protected Interface::Fts::ModifyMenuStructRequestHandler,
+  protected Interface::Fts::RemoveMenuStructRequestHandler
+{
+  Q_OBJECT
+
+public:
+  HandlerMenuStruct(Interface::Dts *dts, Interface::Fts *fts, DatabaseInterface *db);
+  ~HandlerMenuStruct();
+
+  bool init();
+
+  static AvMenuEntry toDds(const Database::AvmMenuStruct &dbEntry);
+
+  /**
+   * Sort the entries in the following way:
+   * - all toplevel entries are at the front ordered by their id
+   * - all non-toplevel entries are at the back ordered by (parentId, rowId, id)
+   */
+  static void sortEntries(MenuStruct &menu);
+
+private:
+  bool initObjects();
+  void reload();
+  QList<MenuStruct>   loadFromDb(bool &status);
+
+
+  void onModifyMenuStructRequest(const rti::core::SampleIdentity &cookie,
+                                 const MenuStruct &request) override final;
+  Core::FunctionReplyObject createMenuStructRequest(const MenuStruct &request);
+  Core::FunctionReplyObject modifyMenuStructRequest(const MenuStruct &request);
+  void onRemoveMenuStructRequest(const rti::core::SampleIdentity &cookie,
+                                 const Core::RemoveElementRequest &request) override final;
+
+private slots:
+  void onDbDeletedAvmMenuStruct(const QVariant &id_);
+
+private:
+  Interface::Dts                    *m_dts;
+  Interface::Fts                    *m_fts;
+  DatabaseInterface                 *m_db;
+  QMap<qint32, ObjectMenuStruct *>   m_objMap;
+
+  LOGGER_T                           m_logger;
+};
+
+} // namespace AudioVideoManagement