feat: Implement weight cutout boundary smoothing for image depth cutout

- Added a new proposal for boundary smoothing in the weight cutout process, differentiating between Split edges and Outline smoothing requirements.
- Introduced a new capability `cutout-boundary-smoothing` to control smoothing strength and default values.
- Updated specifications to define the behavior of boundary-specific smoothing strength and default settings.
- Created tasks to verify the implementation of boundary behavior and asset updates.
- Developed comprehensive tests for depth symmetry and normal scaling to ensure expected behavior and performance.
- Introduced new attributes for normal mapping to facilitate persistent face attributes sharing between depth symmetry and image materials.
- Built a new node group for O Image Depth Symmetry, integrating the new smoothing capabilities and ensuring compatibility with existing workflows.

tests/tools/nodes/test_depth_cutout.py

@@ -162,9 +162,9 @@ def test_depth_cutout_normal_map_only_affects_front_faces():
     evaluated = obj.evaluated_get(bpy.context.evaluated_depsgraph_get())
     mesh = evaluated.to_mesh()
     try:
-        attribute = mesh.attributes["o_normal_scale"]
+        attribute = mesh.attributes["o_normal_reduction"]
         assert attribute.domain == "FACE"
-        weights = [item.value for item in attribute.data]
+        weights = [1.0 - item.value for item in attribute.data]
         assert weights.count(1) == len(obj.data.polygons)
         assert weights.count(0) == len(mesh.polygons) - len(obj.data.polygons)
     finally: