refactor: clean up verbose migration comments

Remove redundant Qt6 migration comments that restate obvious API changes:
- QtConcurrent::run parameter order explanations (preserved where lambda wrapping needed)
- QStringRef/QStringView API changes (shortened to essential info)
- QComboBox::activated signal signature change
- QMap::unite() removal semantics
- QAction include path change
- QMouseEvent/QWheelEvent position() API
- QList/QVector equivalence in Qt6
- QFuture continuation API
- Code generation comments

Preserved comments explaining non-obvious Qt6 behavior or necessary
API migration details.

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

qt6-after/qt6-migrated-legatus/Lts/Tools/ProjectSettingsEditor/main_window.cpp

@@ -13,7 +13,7 @@
 
 #include <NGLLogger/INGLLogger.h>
 
-#include <QtGui/QAction> // Qt6: QAction moved from QtWidgets to QtGui
+#include <QtGui/QAction> // QAction moved to QtGui
 #include <QtCore/QFile>
 #include <QtWidgets/QFileDialog>
 #include <QtCore/QJsonArray>