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.

src/anyimage/menu.py

@@ -23,6 +23,11 @@ class AnyImageImageMenu(bpy.types.Menu):
             text="Convert to Depth Plane",
             icon="MOD_DISPLACE",
         )
+        layout.operator(
+            "anyimage.convert_to_relief_plane",
+            text="Convert to Relief Plane",
+            icon="MOD_DISPLACE",
+        )
         layout.separator()
         layout.operator(
             "anyimage.remove_image_background",