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/LtsWidgets/lts_splash.cpp

@@ -0,0 +1,81 @@
+#include "lts_splash.h"
+
+#include <LtsWidgets/lts_global_wait_dialog.h>
+
+#include <QCoreApplication>
+#include <QFile>
+#include <QEvent>
+
+
+namespace LtsWidgets
+{
+
+Splash::Splash()
+  : QSplashScreen()
+  , m_done(false)
+{
+  static const auto splashFiles =
+  {
+    QStringLiteral(":/project/splash.png"),
+    QStringLiteral(":/project/splash.jpg"),
+  };
+  for (const QString &f : splashFiles)
+  {
+    if (!QFile::exists(f))
+      continue;
+    setPixmap(QPixmap(f));
+    break;
+  }
+}
+
+
+bool Splash::event(QEvent *e)
+{
+  if (e->type() == QEvent::MouseButtonPress ||
+      e->type() == QEvent::MouseButtonRelease ||
+      e->type() == QEvent::MouseButtonDblClick)
+  {
+    e->ignore();
+    return false;
+  }
+
+  return QSplashScreen::event(e);
+}
+
+
+void Splash::setMessage(const QString &message)
+{
+  showMessage(message, Qt::AlignRight | Qt::AlignBottom);
+}
+
+
+void Splash::done()
+{
+  if (m_done)
+    return;
+  m_done = true;
+
+  hide();
+  LtsWidgets::LtsGlobalWaitDialog::getInstance()->setVisible(true); // after the splash has finished, wait dlgs are allowed
+}
+
+
+static Splash *s_splashInstance = nullptr;
+void Splash::cleanupSplashInstance()
+{
+  delete s_splashInstance;
+  s_splashInstance = nullptr;
+}
+
+
+Splash *Splash::getInstance()
+{
+  if (!s_splashInstance)
+  {
+    s_splashInstance = new Splash;
+    qAddPostRoutine(&Splash::cleanupSplashInstance);
+  }
+  return s_splashInstance;
+}
+
+} // namespace LtsWidgets