feat: Add new Geometry Nodes groups for image relief and shadeless shader

- Implemented the "O Image Relief Plane" Geometry Nodes group to create a fixed-base image relief using depth images and various parameters.
- Created the "O Shadeless" shader node group to display color without scene lighting while preserving shadows and reflections.
- Introduced a preview feature for node groups, allowing for interactive visualization of node arrangements in an HTML format.
- Added a template HTML file for rendering node previews with customizable views and controls.

tests/test_clipboard_image.py

@@ -396,43 +396,23 @@ class ClipboardImageTest(unittest.TestCase):
         finally:
             clipboard_image._native_copy_token = original_token
 
-    def test_shadeless_nodes_mix_emission_with_transparency(self):
-        created_nodes = {}
+    def test_plane_paste_uses_shared_material_for_both_shading_modes(self):
+        from anyimage.operators.convert_to_plane import image_plane
 
-        def create_node(node_type):
-            node = SimpleNamespace(location=None, inputs={}, outputs={})
-            if node_type == "ShaderNodeBsdfTransparent":
-                node.outputs["BSDF"] = object()
-            elif node_type == "ShaderNodeEmission":
-                node.inputs["Color"] = object()
-                node.outputs["Emission"] = object()
-            else:
-                node.inputs = [object(), object(), object()]
-                node.outputs["Shader"] = object()
-            created_nodes[node_type] = node
-            return node
-
-        nodes = SimpleNamespace(new=Mock(side_effect=create_node))
-        links = SimpleNamespace(new=Mock())
-        image_node = SimpleNamespace(
-            outputs={"Color": object(), "Alpha": object()},
-        )
-        output_node = SimpleNamespace(inputs={"Surface": object()})
-
-        self.actions._create_shadeless_nodes(
-            nodes,
-            links,
-            image_node,
-            output_node,
-        )
-
-        mix_node = created_nodes["ShaderNodeMixShader"]
-        links.new.assert_any_call(image_node.outputs["Alpha"], mix_node.inputs[0])
-        links.new.assert_any_call(
-            created_nodes["ShaderNodeEmission"].outputs["Emission"],
-            mix_node.inputs[2],
-        )
-        self.assertEqual(links.new.call_count, 5)
+        image = SimpleNamespace(name="Clipboard", size=(16, 8))
+        context = SimpleNamespace(mode="OBJECT", scene=object())
+        for shadeless in (False, True):
+            with (
+                patch.object(self.actions, "create_image_material", return_value="Material") as create_material,
+                patch.object(image_plane, "create_image_plane_object") as create_plane,
+                patch.object(self.actions, "_place_in_view"),
+                patch.object(self.actions, "_select_only"),
+            ):
+                self.actions.add_image_plane(context, image, shadeless=shadeless)
+            create_material.assert_called_once_with(
+                image, image, shadeless=shadeless, scene=context.scene,
+            )
+            self.assertEqual(create_plane.call_args.args[3], "Material")
 
     def test_reference_import_routes_to_image_empty(self):
         context = self.make_context("VIEW_3D")