added ruff test

apps/autocal/tools/preview_snapshot.py

@@ -96,14 +96,12 @@ def main() -> int:
     )
     args = parser.parse_args()
 
-    from PySide6.QtWidgets import QApplication
-
     from orisys_app_shared.i18n import set_locale
     from orisys_app_shared.theme import build_qss
-
     from orisys_autocal.preferences import load_preferences
     from orisys_autocal.ui.pose_preview import configure_compatible_gl
     from orisys_autocal.ui.window import AutoCalMainWindow
+    from PySide6.QtWidgets import QApplication
 
     width, height = (int(part) for part in args.size.lower().split("x"))
 
@@ -223,7 +221,6 @@ def main() -> int:
             # pixels, because a projection that disagrees with the render looks
             # perfectly healthy on its own — that is how the labels drifted off
             # their arrows and the scene sat off to one side without a word.
-            from orisys_autocal.ui.pose_preview import COLOUR
 
             for label, point, colour in _landmarks(panel):
                 screen = panel.preview.project(point)