Add comprehensive tests for image processing and mask functionalities

- Introduced tests for color image handling, ensuring source preservation and premultiplied alpha usage.
- Implemented tests for brush stroke operations, validating segment boundaries and brush anti-aliasing.
- Added tests for frame anti-aliasing, confirming correct rendering behavior with various alpha values and depth settings.
- Created tests for frame projection, ensuring accurate overlap calculations and half-plane clipping.
- Developed tests for image premultiplied retention, verifying behavior during loading and packing processes.
- Added undo functionality tests for mask operations, ensuring single transaction behavior during edits.

src/anyimage/operators/__init__.py

@@ -4,7 +4,7 @@ from .cutout_tool import (
     SelectCutoutSelection,
 )
 from .debug import DebugBen2, DebugDa3, DebugMoge2, DebugUpscale
-from .crop_tool import CLASSES as CROP_TOOL_CLASSES
+from .image_edit_tool import CLASSES as IMAGE_EDIT_TOOL_CLASSES
 from .convert_to_plane import (
     ConvertToDepthPlane,
     ConvertToPlane,
@@ -34,7 +34,7 @@ CLASSES = (
     SelectCutoutSelection,
     RunBackgroundRemoval,
     ClearModels,
-    *CROP_TOOL_CLASSES,
+    *IMAGE_EDIT_TOOL_CLASSES,
     RemoveImageBackground,
     UpscaleImage,
     ConvertToPlane,