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/tools/nodes/test_cutouts.py

@@ -22,7 +22,8 @@ def test_cutout_interfaces_and_thickness_modes(source):
     assert len(set(groups.values())) == 3
     for group in set(groups.values()):
         validate_node_structure(group)
-        assert group.is_modifier and group.get("anyimage_asset_revision") == 11
+        revision = 18 if group == groups["DEPTH_SOLID"] else 11
+        assert group.is_modifier and group.get("anyimage_asset_revision") == revision
         assert not any(node.bl_idname == "GeometryNodeGroup" for node in group.nodes)
         inputs = {item.name: item for item in group.interface.items_tree if item.item_type == "SOCKET" and item.in_out == "INPUT"}
         assert "Shape" not in inputs and "Rim Thickness" not in inputs
@@ -34,6 +35,7 @@ def test_cutout_interfaces_and_thickness_modes(source):
         if "Double Sided" in inputs:
             assert inputs["Double Sided"].default_value
         if group == groups["DEPTH_SOLID"]:
+            assert np.isclose(inputs["Split Threshold"].default_value, 0.1)
             assert np.isclose(inputs["Edge Round"].default_value, 0.2)
             assert inputs["Edge Round"].parent.name == "Options"
             assert list(inputs)[list(inputs).index("Front Inflation") - 1] == "Edge Round"
@@ -44,6 +46,7 @@ def test_cutout_interfaces_and_thickness_modes(source):
         options = [s.name for s in inputs.values() if s.parent and s.parent.name == "Options"]
         expected = ["Cleanup Threshold"]
         if group == groups["DEPTH_SOLID"]:
+            expected.insert(0, "Boundary Smooth")
             expected += ["Reference Depth", "Edge Round", "Front Inflation", "Normal Smooth"]
         elif group == groups["DEPTH_BALLOON"]:
             expected += ["Reference Depth"]