Add cutout shell and volume node assets for depth volume processing

- Implemented `cutout_shell.py` to build front normals and shell positions for balloon geometry.
- Created `cutout_volume.py` to establish smooth center fields and manage balloon surface attributes.
- Introduced `pisa_sr_export.py` for exporting PiSA-SR components with dependencies and asset finalization.

tests/test_cutout_geometry.py

@@ -66,8 +66,8 @@ def test_cutout_node_groups_are_loaded_from_the_asset():
         cutout_object, "load_node_group", return_value=loaded
     ) as load:
         for shape in cutout_shape.CUTOUT_NODE_GROUP_NAMES:
-            assert cutout_object.load_cutout_node_group() is loaded
-            load.assert_called_with(cutout_shape.CUTOUT_NODE_GROUP_NAME)
+            assert cutout_object.load_cutout_node_group(shape) is loaded
+            load.assert_called_with(cutout_shape.CUTOUT_NODE_GROUP_NAMES[shape], asset_revision=11)
         assert load.call_count == 4