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.

tools/nodes/common/depth_surface.py

@@ -327,7 +327,7 @@ def thicken_depth_surface(group, geometry, thickness, normal_smooth=None, *,
     links.new(rim, back_parts.inputs["Geometry"])
     rear = back_parts.outputs["Geometry"]
     if back_mask is not None:
-        rear = store_float_attribute(group, rear, back_mask, 0.0, domain="FACE")
+        rear = store_float_attribute(group, rear, back_mask, 1.0, domain="FACE")
     for value in (
         saved,
         rear,