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.

src/anyimage/operators/cutout_tool/interaction.py

@@ -4,10 +4,10 @@ from ...properties import ai_ready
 from .shape import CUTOUT_SHAPE_LABELS
 
 CUTOUT_SHAPE_BUTTONS = (
-    ("SURFACE", "MESH_GRID"),
-    ("BALLOON", "MESH_UVSPHERE"),
+    ("FLAT", "MESH_GRID"),
+    ("SOLID", "MESH_UVSPHERE"),
     ("DEPTH_BALLOON", "META_BALL"),
-    ("DEPTH_SURFACE", "SURFACE_NCURVE"),
+    ("DEPTH_SOLID", "SURFACE_NCURVE"),
 )
 
 CUTOUT_MESH_DETAIL_SPACING = {