Refactor depth reference handling and cleanup

- Unified reference depth calculation to use a single implementation in common/depth.py.
- Removed server-side reference depth computation and adjusted depth.json to only include image_size and intrinsics.
- Updated depth texture handling to ignore transparent, invalid, and non-positive pixels when calculating reference depth.
- Changed reference depth calculation to use the 95th percentile of valid depth values.
- Adjusted depth direction fitting to return a flat direction when no samples are available.
- Removed cleanup threshold parameters from Cutout and related nodes, simplifying the interface.
- Updated tests to verify new reference depth logic and ensure compatibility with existing functionality.

tests/anyimage/operators/test_plane_conversion.py

@@ -7,6 +7,7 @@ from tests.support.planes import surface
 def test_conversion_preserves_offset_world_placement_and_initializes_inputs(surface, monkeypatch):
     from anyimage.operators.convert_to_plane import object as conversion
     from anyimage.common.image import image_empty_bounds
+    from anyimage.common.depth import reference_depth
     from mathutils import Matrix, Vector
 
     obj, _, _, inputs, image = surface
@@ -22,7 +23,7 @@ def test_conversion_preserves_offset_world_placement_and_initializes_inputs(surf
     bounds = image_empty_bounds(source)
     matrix = source.matrix_world.copy()
     material = bpy.data.materials.new("Conversion")
-    metadata = {"image_size": (16, 8), "reference_depth": 2.0,
+    metadata = {"image_size": (16, 8),
                 "intrinsics": ((4, 0, 5), (0, 4, 3), (0, 0, 1))}
     result = conversion.create_depth_plane_object(
         bpy.context, source, 2, material, image, metadata, "DEPTH")
@@ -40,7 +41,7 @@ def test_conversion_preserves_offset_world_placement_and_initializes_inputs(surf
     assert modifier[inputs["Depth Image"].identifier] == image
     assert modifier[inputs["Depth Mask"].identifier] is True
     assert modifier[inputs["Reference Depth"].identifier] == pytest.approx(
-        2 * modifier[inputs["Uniform Scale"].identifier])
+        reference_depth(image) * modifier[inputs["Uniform Scale"].identifier])
     assert result.data.materials[0] == material
 
 
@@ -60,7 +61,7 @@ def test_failed_modifier_initialization_removes_partial_object(surface, monkeypa
         raise RuntimeError("input failed")
 
     monkeypatch.setattr(conversion, "set_modifier_input", fail)
-    metadata = {"image_size": (16, 8), "reference_depth": 2,
+    metadata = {"image_size": (16, 8),
                 "intrinsics": ((4, 0, 5), (0, 4, 3), (0, 0, 1))}
     with pytest.raises(RuntimeError, match="input failed"):
         conversion.create_depth_plane_object(bpy.context, source, 2, material, image, metadata, "DEPTH")