- Merged test_mainwindow.cpp tests into test_main.cpp to have single main()
- Removed test_mainwindow.cpp from CMakeLists.txt test executable
- Qt test executables should have only one main() via QTEST_MAIN()
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Entire-Checkpoint: 0f6858921c53