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/tools/nodes/test_depth_surface_split.py

@@ -87,18 +87,6 @@ def test_midpoint_selects_relative_ray_jump_and_preserves_faces():
     assert set(np.round(coords[:, 1], 4)) == {2.0, -2.0}
 
 
-def test_cleanup_keeps_split_parts_of_a_large_source_island():
-    obj, set_value = surface(wrapper=True)
-    set_value("Cleanup Threshold", 110.0)
-    assert len(evaluated(obj)[1]) == 8
-    set_value("Depth Split", 0.5)
-    assert len(evaluated(obj)[1]) == 8
-    set_value("Thickness", 0.2)
-    assert_closed(evaluated(obj)[1])
-    set_value("Cleanup Threshold", 210.0)
-    assert len(evaluated(obj)[1]) == 0
-
-
 @pytest.mark.parametrize("depth_scale", [0.0, 2.0])
 def test_split_topology_uses_depth_before_display_scaling(depth_scale):
     obj, set_value = surface(step=4.0)
@@ -112,7 +100,7 @@ def test_split_topology_uses_depth_before_display_scaling(depth_scale):
 
 
 def test_full_wrapper_keeps_closed_shell():
-    obj, set_value = surface(wrapper=True)
+    obj, set_value = surface()
     set_value("Depth Split", 0.5)
     set_value("Thickness", 0.2)
     coords, faces = evaluated(obj)
@@ -196,7 +184,7 @@ def test_source_surface_sampling_preserves_depth_on_side_walls():
 @pytest.mark.parametrize("thickness", [0.0, 0.2])
 @pytest.mark.parametrize("split", [0.0, 0.5])
 def test_temporary_fields_are_removed_and_user_attributes_survive(thickness, split):
-    obj, set_value = surface(wrapper=True)
+    obj, set_value = surface()
     obj.data.attributes.new("o_depth_probe", "FLOAT", "POINT")
     attribute = obj.data.attributes.new("o_user_weight", "FLOAT", "POINT")
     obj.data.attributes.new(".o_anyimage_user_weight", "FLOAT", "POINT")