feat(selection): separate selection geometry from image content processing

- Introduced a new design for selection rasterization that decouples the selection geometry from the image content, ensuring that the SelectionMask is independent of the source image's alpha and color.
- Updated the `rasterize_selection_path` function to only accept selection paths and image dimensions, removing parameters related to source alpha and alpha thresholds.
- Implemented a new approach for handling selection paths using non-zero winding fill, ensuring overlapping areas are preserved.
- Enhanced performance by utilizing a scanline algorithm for rasterization, significantly reducing processing time for high-resolution images.
- Updated internal documentation and added comprehensive tests to validate the new behavior and performance improvements.
- Ensured backward compatibility by maintaining existing interfaces where necessary while introducing breaking changes in the selection processing logic.

tools/node_assets/build_material_layers.py

@@ -2,7 +2,7 @@
 
 import bpy
 
-from anyimage.common.object import (
+from anyimage.common.material import (
     DEPTH_MATERIAL_NODE_GROUP_NAME,
     IMAGE_MATERIAL_NODE_GROUP_NAME,
 )