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.

src/anyimage/operators/image_tool/box.py

@@ -0,0 +1,24 @@
+import bpy
+
+from ..common.image_edit import draw_image_mask_settings
+from .edit_mask import EditImageMask
+
+
+class ImageBoxTool(bpy.types.WorkSpaceTool):
+    bl_space_type = "VIEW_3D"
+    bl_context_mode = "OBJECT"
+    bl_idname = "anyimage.image_box"
+    bl_label = "Image Box"
+    bl_description = "Edit an Image Empty with a rectangular mask"
+    bl_icon = "ops.sculpt.border_mask"
+    bl_operator = EditImageMask.bl_idname
+    bl_keymap = (
+        (
+            EditImageMask.bl_idname,
+            {"type": "LEFTMOUSE", "value": "PRESS"},
+            {"properties": [("gesture", "BOX")]},
+        ),
+    )
+
+    def draw_settings(context, layout, _tool):
+        draw_image_mask_settings(context, layout, "image_box_refine_selection")