Add operators for model downloading and surface generation

- Implemented `DownloadModel` and `DownloadRequiredModels` operators for downloading models.
- Created `ClearModels` operator to clear model resources.
- Added `ConvertToSurface` operator for converting image empties into textured surfaces.
- Introduced `GenerateDa3Surface` and `GenerateMoge2Surface` operators for generating surfaces using DA3 and MoGe-2 models respectively.
- Developed utility functions for handling image mesh data, assigning attributes, and managing geometry nodes.
- Established runtime configuration and post-installation model downloading in `runtime.py`.

tools/validate_depth_plane_asset.py

@@ -11,20 +11,20 @@ sys.path.insert(
     str(next((PROJECT_ROOT / "src" / "snapform" / "wheels").glob("blendjob-*.whl"))),
 )
 
-from snapform.blender.depth_plane import (
+from snapform.operators.material import (
     DEPTH_PLANE_MATERIAL_NODE_GROUP_NAME,
-    material_color_space_name,
     SHADELESS_NODE_GROUP_NAME,
     SURFACE_MATERIAL_NODE_GROUP_NAME,
-    add_depth_plane_processing,
     create_material,
     get_modifier_input,
     load_depth_plane_node_group,
+    material_color_space_name,
     modifier_input_driver_path,
     modifier_input_identifier,
     set_modifier_input,
 )
-from snapform.blender.surface import load_geometry_node_group
+from snapform.operators.depth_plane.build import add_depth_plane_processing
+from snapform.operators.surface import load_geometry_node_group
 
 
 def main():