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.

src/anyimage/operators/cutout_tool/interaction.py

@@ -6,7 +6,7 @@ from .shape import CUTOUT_SHAPE_LABELS
 CUTOUT_SHAPE_BUTTONS = (
     ("FLAT", "MESH_GRID"),
     ("SOLID", "MESH_UVSPHERE"),
-    ("DEPTH_BALLOON", "META_BALL"),
+    ("DEPTH_SYMMETRY", "META_BALL"),
     ("DEPTH_SOLID", "SURFACE_NCURVE"),
 )