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_moge_depth_plane.py

@@ -15,16 +15,14 @@ sys.path.insert(
     str(next((PROJECT_ROOT / "src" / "snapform" / "wheels").glob("blendjob-*.whl"))),
 )
 
-import snapform.blender.depth_plane as depth_plane
-
-from snapform.blender.depth_plane import (
+from snapform.operators.image import create_color_image
+from snapform.operators.material import (
     MOGE_DEPTH_PLANE_NODE_GROUP_NAME,
     MOGE_MATERIAL_NODE_GROUP_NAME,
-    build_moge2_depth_plane,
-    create_color_image,
     get_modifier_input,
     modifier_input_identifier,
 )
+from snapform.operators.depth_plane.build import build_moge2_depth_plane
 
 
 def validate_single_frame_source_types():