Test Organisation

[pmaasz]

• tests/run_all_tests.py runs everything serially with no parallelism and no slow/integration markers.
• test_aberrations_quick.py is not a duplicate of test_aberrations.py — it's a small script that prints, not a unittest. Move it to scripts/ or delete.
• GUI tests (tests/test_gui.py) rely on QApplication() and require a display. No xvfb hook in the project, so CI on a headless runner would fail silently.
• Dead tests target the dead tkinter code: test_fix_removal.py, test_gui_controllers.py, test_visualization.py. Delete when the tkinter code goes.