Qt6 Migration: Merge latest Qt5 devel content and apply migration fixes

- Merged 292 changed files from dlbo snapshot
- Fixed IDL enum collisions (PortType, PdmEventType)
- Fixed Grantlee template for C++11 scoped enums
- Fixed CMake VERSION_GREATER syntax
- Added missing directories (THP, LtsRestClient, etc.)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Lts/Tools/RestClientUi/main.cpp

@@ -0,0 +1,22 @@
+/*
+ * main for RestClientUi
+ * $Id$
+ * $HeadURL$
+ * $Author$
+ * Created by Hannes Fritsche, ESZS, 2026-08-25
+ */
+
+#include <QApplication>
+#include "main_window.h"
+
+// Documentation on how to use it can be found at https://confluence-classified.rh-int.de/spaces/LEG/pages/207919552/HOWTO+RestClientUi+Tool
+
+int main(int argc, char *argv[])
+{
+    QApplication app(argc, argv);
+
+    MainWindow window;
+    window.show();
+
+    return app.exec();
+}