Complete Qt6 migration: full clean build green across groups G1-G12 incl. runtime plugin set

new_docker_build.sh gains Group 12 (212 GUI/Data plugins); fixes LtsUtilsGuiDds visibility (LTO-stripped exports), LtsProjectionWorkstation unity name shadow, 6 unity-off dirs (dup file-scope statics, ddsftc INTERFACE sources) and reconfigures BUILD_FILTERMANAGEMENT/BUILD_PLUGINS_SERVICEMONITOR=ON

qt6-after/qt6-migrated-legatus/Lts/Proxies/TrainingAreaBase/ppm_handler.cpp

@@ -50,7 +50,7 @@ void PpmHandler::onParticipantPositionChanged(const ParticipantManagement::Parti
 
    ParticipantManagement::Participant participant = m_ppmDtc->participant(data.participantId);
    int equipNo = 0;
-   if (participant.equipmentNumber.is_set())
+   if (participant.equipmentNumber.has_value())
      equipNo = participant.equipmentNumber.get();
 
    if (equipNo > 0)