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/Plugins/OcSituationClient/Gui/System/osc_settings.cpp

@@ -9,6 +9,7 @@
 #include <SituationMapPlugin/situation_map_gui_plugin_interface.h>
 #include <PluginInterfaces/gui_plugin_interface.h>
 #include <QtCore/QDebug>
+#include <QAudioOutput>
 
 namespace OcSituationClient
 {
@@ -68,8 +69,8 @@ Settings::Settings(LtsSession::LtsSession *session, QWidget *parent)
   loadOperatorSettings();
 
   
-  m_mediaplayer->setMedia(QUrl(QLatin1String("qrc:/beep.wav")));
-  m_mediaplayer->setVolume(100);
+  m_mediaplayer->setSource(QUrl(QLatin1String("qrc:/beep.wav")));
+  m_mediaplayer->audioOutput()->setVolume(1.0f);
 
   setOnlineHelpFilename(QStringLiteral("OC-Settings"));
 }