Add tests and implement boundary smoothing and cutout functionality

- Introduced tests for boundary smoothing in `test_boundary_smoothing.py`, verifying that smoothing reduces stair-step artifacts while preserving boundary integrity.
- Added tests for cutout boundary behavior in `test_cutout_boundary.py`, ensuring proper handling of boundary triangles and normal blending.
- Created `test_temporary_attributes.py` to check the cleanup of temporary attributes across depth modifier branches, ensuring no warnings are raised.
- Implemented point culling functionality in `test_validity.py`, confirming that invalid points are removed without affecting adjacent geometry.
- Developed boundary smoothing logic in `boundary_smoothing.py`, allowing for depth smoothing while maintaining edge integrity.
- Added cutout boundary management in `cutout_boundary.py`, including functions for removing boundary triangles and tapering thickness profiles.
- Implemented validity checks in `validity.py` to ensure proper deletion of invalid vertices and associated wire edges.

tests/anyimage/operators/test_plane_conversion.py

@@ -11,7 +11,7 @@ def test_conversion_preserves_offset_world_placement_and_initializes_inputs(surf
 
     obj, _, _, inputs, image = surface
     group = obj.modifiers[0].node_group
-    monkeypatch.setattr(conversion, "load_node_group", lambda name: group)
+    monkeypatch.setattr(conversion, "load_node_group", lambda name, *, asset_revision: group)
     source = bpy.data.objects.new("Offset Image", None)
     source.empty_display_type = "IMAGE"
     source.data = image
@@ -48,7 +48,7 @@ def test_failed_modifier_initialization_removes_partial_object(surface, monkeypa
     from anyimage.operators.convert_to_plane import object as conversion
 
     obj, _, _, _, image = surface
-    monkeypatch.setattr(conversion, "load_node_group", lambda name: obj.modifiers[0].node_group)
+    monkeypatch.setattr(conversion, "load_node_group", lambda name, *, asset_revision: obj.modifiers[0].node_group)
     source = bpy.data.objects.new("Source", None)
     source.empty_display_type = "IMAGE"
     source.data = image