Refactor Cutout and Image Editing Logic

- Renamed "Base Plane Depth" to "Reference Depth" across validate_cutout.py for consistency.
- Introduced a new specification for Cutout mesh sampling to ensure source pixel spacing is preserved and limits are applied correctly.
- Unified naming conventions for image editing results to maintain consistency across Remove Background, Upscale, and Crop operations.
- Updated the handling of Refine Selection to ensure it retains the original bounds and does not apply unnecessary cropping.
- Enhanced material generation logic to connect image color directly to IOR Level, improving the rendering of dark areas.
- Established clear requirements for geometry depth controls and image result materials to ensure consistent behavior across different components.
- Removed outdated logic and ensured all changes are documented and tested for regression.

src/anyimage/common/selection.py

@@ -3,6 +3,7 @@
 import json
 import math
 from dataclasses import dataclass
+from pathlib import Path
 
 
 class ImageEditWarning(ValueError):
@@ -86,6 +87,29 @@ class SelectionMask:
         return result
 
 
+def save_selection_mask(path, selection_mask):
+    """Save one local Selection Mask beside a prepared image input."""
+    import numpy as np
+
+    path = Path(path).parent / "selection-mask.npy"
+    np.save(path, selection_mask.values, allow_pickle=False)
+    return path
+
+
+def load_selection_mask(path, bounds):
+    """Load a local Selection Mask sidecar without allowing object data."""
+    import numpy as np
+
+    values = np.load(Path(path), allow_pickle=False)
+    return SelectionMask(values, bounds)
+
+
+def cleanup_selection_mask(path):
+    """Remove a local Selection Mask sidecar."""
+    if path:
+        Path(path).unlink(missing_ok=True)
+
+
 def selection_path_bounds(points):
     import numpy as np