Add new node asset scripts for geometry and shader operations

- Implemented `build_mesh_plane.py` to create a geometry node group for mesh planes with customizable parameters.
- Created `build_shadeless.py` for a shader node group that displays color without scene lighting while preserving shadows and reflections.
- Added `validate.py` to validate the integrity of the newly created node groups and their inputs.
- Introduced `validate_cutout.py` to ensure the functionality of cutout node groups and their dependencies.
- Developed `validate_mesh_plane.py` to test the mesh plane creation and its modifier settings.

pack.py

@@ -105,6 +105,11 @@ def _build_extension(platform, wheels):
                 continue
             if "__pycache__" in source_path.parts:
                 continue
+            if (
+                source_path.suffix.startswith(".blend")
+                and source_path.suffix != ".blend"
+            ):
+                continue
             relative_path = source_path.relative_to(SOURCE_DIR)
             if relative_path.parts[0] == "wheels":
                 continue