Add image selection refinement functionality with BEN2 integration

- Implemented viewport.py for handling 3D view projections, gestures, and overlay drawing.
- Created refine_image_selection.py to manage the refinement of gesture masks and output image bounds.
- Added selection module with refine_selection.py to process and crop images based on alpha channel visibility.
- Introduced __init__.py for selection module to expose refine_selection function.

tests/test_node_assets.py

@@ -15,8 +15,8 @@ class NodeAssetsTest(unittest.TestCase):
         self.assertEqual(offenders, [])
 
     def test_runtime_node_group_entries_load_assets(self):
-        object_source = (
-            SOURCE_ROOT / "common" / "object.py"
+        material_source = (
+            SOURCE_ROOT / "common" / "material.py"
         ).read_text(encoding="utf-8")
         mesh_plane_source = (
             SOURCE_ROOT / "operators" / "convert_to_plane" / "mesh_plane.py"
@@ -24,7 +24,7 @@ class NodeAssetsTest(unittest.TestCase):
         depth_plane_source = (
             SOURCE_ROOT / "operators" / "convert_to_plane" / "object.py"
         ).read_text(encoding="utf-8")
-        self.assertIn("return load_node_group(group_name)", object_source)
+        self.assertIn("return load_node_group(group_name)", material_source)
         self.assertIn(
             "load_node_group(MESH_PLANE_NODE_GROUP_NAME)",
             mesh_plane_source,