Merge feature/qt6-migration-basis-modules-services into feature/qt6-migration-basis-modules

Resolves 17 conflicts against legacy Qt5 semantics; validates with BUILD_RTI=ON BUILD_GRANTLEE=ON.

qt6-after/qt6-migrated-legatus/.forward-declarations/include/OperatorManagement/opm_ftc.h

@@ -0,0 +1,21 @@
+#ifndef OPM_FTC_H
+#define OPM_FTC_H
+
+// Stub header for OperatorManagement FTC functionality
+// This file is part of FilterManagement which is excluded from build
+// For non-FilterManagement builds, we provide this stub
+
+#include <QtCore/QString>
+#include <QtCore/QObject>
+
+// Forward declarations and stubs for FTC (Filter/Translation/Conversion)
+// Actual implementation is in FilterManagement plugin
+
+class OpmFtc
+{
+public:
+    virtual ~OpmFtc() = default;
+    // Stub methods - actual implementation in FilterManagement
+};
+
+#endif // OPM_FTC_H