Refactor image handling and update foreground processing

- Changed the logic in `remove_background_faces` to keep only faces with all foreground vertices.
- Updated background job to save foreground images with a new naming convention (`color.0001.png`).
- Replaced `copy_frames` with `copy_color_images` in various jobs to ensure consistent image naming.
- Introduced a new function `copy_color_images` to handle the copying of images with a specific naming format.
- Updated the BEN2 model to save output images with a new prefix for better clarity.
- Modified tests to reflect changes in image naming and processing logic.
- Added a new shadeless node group for improved material handling in geometry nodes.
- Enhanced validation scripts to check for new image naming conventions and ensure proper functionality.

tests/test_server.py

@@ -376,7 +376,7 @@ class ServerTest(unittest.TestCase):
             )
             status = self.wait_for_job(context)
             self.assertTrue(
-                (context.directory / "frame.0001.jpg").is_file()
+                (context.directory / "color.0001.jpg").is_file()
             )
 
         self.assertEqual(status["state"], "succeeded")