Add new tests and functionality for image processing and geometry handling

- Introduced color_image.py for preparing standalone color images for tests.
- Added hdr_image.py to create HDR textures for testing.
- Implemented test_image_depth_panorama.py to evaluate panorama topology, UVs, and depth discontinuities.
- Created test_shadeless.py to validate the opacity and HDR color endpoints of the Shadeless group.
- Developed moge3_export.py for exporting dynamic MoGe-3 backbone and ONNX graphs.
- Added material.py to inherit material slots onto generated geometry.
- Built image_depth_panorama.py to construct a quad panorama with depth separation and sampling.

tools/nodes/groups/shadeless.py

@@ -14,6 +14,9 @@ def build_shadeless_group():
     group.interface.new_socket(
         name="Color", in_out="INPUT", socket_type="NodeSocketColor"
     )
+    alpha = group.interface.new_socket(name="Alpha", in_out="INPUT", socket_type="NodeSocketFloat")
+    alpha.default_value, alpha.min_value, alpha.max_value = 1.0, 0.0, 1.0
+    alpha.subtype = "FACTOR"
     nodes = group.nodes
     links = group.links
     group_input = nodes.new("NodeGroupInput")
@@ -67,7 +70,15 @@ def build_shadeless_group():
     links.new(shader_factor.outputs[0], mix.inputs["Fac"])
     links.new(diffuse.outputs["BSDF"], mix.inputs[1])
     links.new(emission.outputs["Emission"], mix.inputs[2])
-    links.new(mix.outputs["Shader"], group_output.inputs["Shader"])
+    transparent = nodes.new("ShaderNodeBsdfTransparent")
+    transparent.location = (550.0, -200.0)
+    alpha_mix = nodes.new("ShaderNodeMixShader")
+    alpha_mix.location = (850.0, 100.0)
+    group_output.location = (1100.0, 100.0)
+    links.new(group_input.outputs["Alpha"], alpha_mix.inputs["Fac"])
+    links.new(transparent.outputs["BSDF"], alpha_mix.inputs[1])
+    links.new(mix.outputs["Shader"], alpha_mix.inputs[2])
+    links.new(alpha_mix.outputs["Shader"], group_output.inputs["Shader"])
     group.color_tag = "SHADER"
     group.description = (
         "Display color without scene lighting while preserving shadows "