Major port Qt4 to Qt6

- Updated header inclusions from QtGui to QtWidgets for consistency and compatibility with Qt 5 and later.
- Replaced deprecated QApplication::desktop() with QApplication::primaryScreen() for obtaining screen DPI.
- Modified MyOutputHandler to use QMessageLogContext and QString for improved logging.
- Changed QMatrix to QTransform for image rotation in ImageCutout class.
- Updated various debug statements to use toLocal8Bit() instead of toAscii() for better string handling.
- Refactored several classes to use QElapsedTimer instead of QTime for performance measurement.
- Ensured all operator overloads in Section and Tag classes are marked as const for better const-correctness.

.gitignore

@@ -15,8 +15,8 @@ CTestTestfile.cmake
 install_manifest.txt
 Makefile
 
-ClippingStation.app/
-ClippingStation.app
+Clipping\ Station.app/
+Clipping\ Station.app
 
 # qmake / Qt Creator
 *.pro.user*