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.

tests/tools/nodes/test_temporary_attributes.py

@@ -27,7 +27,9 @@ def test_depth_attribute_cleanup_has_no_warnings(kind):
                 assert mesh.vertices
                 assert not {a.name for a in mesh.attributes} & {
                     ".o_anyimage_depth_cut", ".o_anyimage_original_boundary",
+                    "_o_anyimage_depth_cut",
                 }
+                assert not any(a.name.startswith("_o_") for a in mesh.attributes)
                 assert not list(modifier.node_warnings), [
                     warning.message for warning in modifier.node_warnings
                 ]