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/Common/LtsRestClient/lts_rest_client.cpp

@@ -0,0 +1,172 @@
+/**
+ * Lightweight REST Client Framework
+ * $Id$
+ * $HeadURL$
+ * $Author$
+ * Created by Hannes Fritsche, ESZS, 2026-08-21
+ */
+
+#include "lts_rest_client.h"
+#include <QTimer>
+#include <QUrl>
+#include <QtNetwork/QNetworkAccessManager>
+#include <QtNetwork/QNetworkReply>
+#include <QtNetwork/QNetworkRequest>
+
+namespace LtsCommon
+{
+
+LtsRestClient::LtsRestClient(const QString &baseUrl, QObject *parent)
+  : QObject(parent)
+  , m_baseUrl(baseUrl)
+  , m_manager(new QNetworkAccessManager(this))
+{
+}
+
+void LtsRestClient::ping(PingSuccessCallback onSuccess, ErrorCallback onError, int timeoutMs)
+{
+  const QNetworkRequest request((QUrl(m_baseUrl)));
+  QNetworkReply *reply = m_manager->head(request);
+
+  if (!reply)
+  {
+    if (onError)
+      onError(QStringLiteral("Failed to initiate ping."));
+
+    return;
+  }
+
+  // 1. Setup the timer (parented to reply for auto-cleanup)
+  QTimer *timeoutTimer = new QTimer(reply);
+  timeoutTimer->setSingleShot(true);
+
+  // 2. Connect the timeout signal to abort the request
+  connect(timeoutTimer, &QTimer::timeout, this, [reply]()
+  {
+    if (reply && reply->isRunning())
+      reply->abort(); // Triggers finished() with OperationCanceledError
+  });
+
+  // 3. Connect the finished signal to handle the response
+  connect(reply,
+          &QNetworkReply::finished,
+          this,
+          [reply, timeoutTimer, onSuccess, onError]()
+  {
+    timeoutTimer->stop();
+    reply->deleteLater();
+
+    if (reply->error() != QNetworkReply::NoError)
+    {
+      if (onError)
+      {
+        if (reply->error() == QNetworkReply::OperationCanceledError)
+          onError(QStringLiteral("Ping timed out."));
+        else
+          onError(reply->errorString());
+      }
+
+      return;
+    }
+
+    const int statusCode = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
+
+    if (onSuccess)
+      onSuccess(statusCode);
+  });
+
+  // 4. Start the timer only after all connections are successfully established
+  timeoutTimer->start(timeoutMs);
+}
+
+void LtsRestClient::get(const QString &endpoint, SuccessCallback onSuccess, ErrorCallback onError)
+{
+  sendRequest(QStringLiteral("GET"), endpoint, QByteArray(), onSuccess, onError);
+}
+
+void LtsRestClient::post(const QString &endpoint, const QJsonDocument &json, SuccessCallback onSuccess, ErrorCallback onError)
+{
+  sendRequest(QStringLiteral("POST"), endpoint, json.toJson(), onSuccess, onError);
+}
+
+void LtsRestClient::put(const QString &endpoint, const QJsonDocument &json, SuccessCallback onSuccess, ErrorCallback onError)
+{
+  sendRequest(QStringLiteral("PUT"), endpoint, json.toJson(), onSuccess, onError);
+}
+
+void LtsRestClient::del(const QString &endpoint, SuccessCallback onSuccess, ErrorCallback onError)
+{
+  sendRequest(QStringLiteral("DELETE"), endpoint, QByteArray(), onSuccess, onError);
+}
+
+void LtsRestClient::sendRequest(const QString &method, const QString &endpoint, const QByteArray &data, SuccessCallback onSuccess, ErrorCallback onError)
+{
+  QUrl url(m_baseUrl);
+  url.setPath(url.path() + endpoint);
+
+  QNetworkRequest request(url);
+  request.setHeader(QNetworkRequest::ContentTypeHeader, QStringLiteral("application/json"));
+
+  QNetworkReply *reply = nullptr;
+
+  if (method == QStringLiteral("GET"))
+    reply = m_manager->get(request);
+  else if (method == QStringLiteral("POST"))
+    reply = m_manager->post(request, data);
+  else if (method == QStringLiteral("PUT"))
+    reply = m_manager->put(request, data);
+  else if (method == QStringLiteral("DELETE"))
+    reply = m_manager->deleteResource(request);
+
+  if (!reply)
+  {
+    if (onError)
+      onError(QStringLiteral("Failed to initiate request."));
+
+    return;
+  }
+
+  connect(reply,
+          &QNetworkReply::finished,
+          this,
+          [reply, onSuccess, onError]()
+  {
+    reply->deleteLater();
+
+    // Handle network errors
+    if (reply->error() != QNetworkReply::NoError)
+    {
+      if (onError)
+        onError(reply->errorString());
+
+      return;
+    }
+
+    // Handle HTTP errors
+    const int statusCode = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
+    if (statusCode >= 400)
+    {
+      if (onError)
+        onError(QStringLiteral("HTTP Error %1").arg(statusCode));
+
+      return;
+    }
+
+    // Parse JSON safely
+    QJsonParseError parseError;
+    const QJsonDocument doc = QJsonDocument::fromJson(reply->readAll(), &parseError);
+
+    if (parseError.error != QJsonParseError::NoError)
+    {
+      if (onError)
+        onError(QStringLiteral("JSON Parse Error: ") + parseError.errorString());
+
+      return;
+    }
+
+    if (onSuccess)
+      onSuccess(doc);
+  });
+}
+
+} // namespace LtsCommon