Refactor image processing and cutout functionalities

- Updated the naming convention for upscaled images to include underscores and file extensions.
- Renamed properties related to cutout pixel size to point spacing for clarity.
- Adjusted alpha region calculations to use a half-alpha threshold for better accuracy.
- Enhanced the handling of foreground mesh masks to consider half-alpha values.
- Introduced new functions for unbounded selections and cutout images, ensuring proper handling of source and selection images.
- Improved test coverage for cutout functionalities, including bounds mapping and alpha preservation.
- Updated tests to reflect changes in naming conventions and functionality adjustments.

src/anyimage/operators/upscale.py

@@ -147,7 +147,7 @@ class UpscaleImage(JobOperatorBase, bpy.types.Operator):
             replaced_image.use_fake_user = False
             if int(replaced_image.users) == 0:
                 bpy.data.images.remove(replaced_image, do_unlink=True)
-        result_image.name = f"{image_base_name(source_image)}.upscale"
+        result_image.name = f"{image_base_name(source_image)}_upscale.png"
         result_image.anyimage_upscale_source = source_image
         model_label = upscale_model_label(self.model)
         if getattr(self, "_rebuild_from_original", False):