feat(node_assets): add image plane geometry nodes and validation scripts

- Implemented `image_plane.py` to build the Image Plane Geometry Nodes group with customizable parameters for geometry, subdivide, and thickness.
- Created `image_plane_validation.py` to validate the functionality of the image plane, ensuring correct geometry generation and material assignment.
- Developed `material_layers.py` to construct shader node groups for image materials, including depth and normal handling.
- Authored `plane_layouts.py` to define node arrangements for image geometry assets.
- Introduced `shadeless.py` to create a shadeless shader node group that displays color without scene lighting while preserving shadows and reflections.

tests/test_model_download.py

@@ -104,14 +104,14 @@ class ModelDownloadTest(unittest.TestCase):
 
         progress, reports = self.create_progress(
             tqdm_type=FakeTqdmWithRate,
-            label="da3 small",
+            label="MoGe-2",
         )
 
         progress.update(50)
 
         self.assertEqual(
             reports[-1][1],
-            "Downloading da3 small 13.4 MB/s",
+            "Downloading MoGe-2 13.4 MB/s",
         )
 
     def test_progress_callback_has_no_eta_or_state_protocol(self):