Optimize Cutout Geometry Nodes

- Refactor Depth Cutout to reuse the projected outline field, reducing redundant boundary calculations and improving performance.
- Derive the center field from shared low-frequency fields, eliminating an unnecessary blur operation.
- Implement triangle-only strip cleanup for Depth Cutout, as the input is confirmed to be triangulated.
- Short-circuit zero-thickness branches in both Cutout and Depth Cutout to avoid unnecessary geometry generation.
- Standardize internal attribute naming with a new `_o_` prefix and implement wildcard cleanup for temporary attributes.
- Update relevant tests to ensure functionality remains consistent and validate changes against existing behavior.

tools/nodes/check.py

@@ -77,7 +77,11 @@ def check_asset_library(asset_path):
             )
             assert not {attribute.name for attribute in result.attributes} & {
                 ".o_anyimage_depth_cut", ".o_anyimage_original_boundary",
+                "_o_anyimage_depth_cut",
             }, node_group.name
+            assert not any(
+                attribute.name.startswith("_o_") for attribute in result.attributes
+            ), node_group.name
         finally:
             evaluated.to_mesh_clear()
             bpy.data.objects.remove(obj, do_unlink=True)