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/Lts/Services/Messaging/msg_ftc.h

@@ -0,0 +1,17 @@
+#ifndef MSG_FTC_H
+#define MSG_FTC_H
+
+// Stub file for msg_ftc.h - generated code placeholder
+// This file is auto-generated from msg_service.xml when BUILD_GRANTLEE=ON
+// For BUILD_GRANTLEE=OFF, this stub allows compilation to proceed
+
+namespace Messaging {
+namespace Dds {
+
+// Forward declarations - actual definitions in generated code
+class Ftc;
+
+} // namespace Dds
+} // namespace Messaging
+
+#endif // MSG_FTC_H