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/ParticipantManagement/web_socket_handler.cpp

@@ -0,0 +1,115 @@
+/**
+  * Websocket interface to participant positions
+  * $Id$
+  * $HeadURL$
+  * $Author$
+  * Created by Justus Hertel, SLSE, 2020-07-08
+  */
+
+#include "web_socket_handler.h"
+
+#include <QWebSocket>
+#include <QJsonObject>
+#include <QJsonDocument>
+
+#include <ParticipantManagement/ppm.hpp>
+
+namespace ParticipantManagement
+{
+
+WebSocketHandler::WebSocketHandler(QObject *parent)
+  : QObject(parent)
+  , m_webSocketServer(new QWebSocketServer(QStringLiteral("ParticipantPositionsSocket"), QWebSocketServer::NonSecureMode, this))
+  , m_logger(getLogger(QStringLiteral("WebSocketHandler")))
+{}
+
+WebSocketHandler::~WebSocketHandler()
+{
+  for (const auto& ws : qAsConst(m_webSockets))
+  {
+    ws->disconnect(this);
+  }
+  m_webSockets.clear();
+}
+
+bool WebSocketHandler::init(quint16 listenPort)
+{
+  if (!m_webSocketServer->listen(QHostAddress::Any, listenPort))
+  {
+    WARNING_LOG(m_logger) << "Can not listen on port " << listenPort << " - aborting";
+    return false;
+  }
+
+  connect(m_webSocketServer, &QWebSocketServer::newConnection,
+          this, &WebSocketHandler::onNewConnection);
+
+  INFO_LOG(m_logger) << "Listening on port " << m_webSocketServer->serverPort();
+  return true;
+}
+
+bool WebSocketHandler::init(const QPair<quint16, quint16> &portRange)
+{
+  for (quint16 currentPort = portRange.first; currentPort <= portRange.second; ++currentPort)
+  {
+    if (init(currentPort))
+      return true;
+  }
+
+  return init();
+}
+
+bool WebSocketHandler::sendTelegramInternal(const ParticipantPosition &pos, int eqNo) const
+{
+  QJsonObject obj;
+  obj[QStringLiteral("participantId")]   = pos.participantId();
+  obj[QStringLiteral("equipmentNumber")] = eqNo;
+  obj[QStringLiteral("lat")]             = pos.pos().lat();
+  obj[QStringLiteral("lon")]             = pos.pos().lon();
+  obj[QStringLiteral("height")]          = pos.pos().z();
+
+  const QString jsonStr = QString::fromUtf8(QJsonDocument(obj).toJson(QJsonDocument::Compact));
+
+  bool ret = false;
+  for (const auto &wsw : qAsConst(m_webSockets))
+  {
+    if (wsw->sendTextMessage(jsonStr))
+      ret = true;
+  }
+  return ret;
+}
+
+void WebSocketHandler::onNewConnection()
+{
+  QWebSocket *ws = m_webSocketServer->nextPendingConnection();
+  if (!ws)
+    return;
+
+  connect(ws, &QWebSocket::disconnected,
+          this, &WebSocketHandler::onWebSocketDisconnected);
+
+  m_webSockets += ws;
+
+  INFO_LOG(m_logger) << "New websocket connected";
+}
+
+void WebSocketHandler::onWebSocketDisconnected()
+{
+  QWebSocket *ws = qobject_cast<QWebSocket *>(sender());
+  if (!ws)
+    return;
+
+  m_webSockets.removeAll(ws);
+  ws->deleteLater();
+
+  INFO_LOG(m_logger) << "A websocket disconnected";
+}
+
+bool WebSocketHandler::sendPosition(const ParticipantPosition &participantPosition, int equipmentNumber) const
+{
+  if (!isConnected() || m_webSockets.isEmpty())
+    return false;
+
+  return sendTelegramInternal(participantPosition, equipmentNumber);
+}
+
+}