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/support/depth_surface.py

@@ -8,7 +8,7 @@ import numpy as np
 from tests.support.nodes import CUTOUT_BUILDERS
 
 
-def surface(*, step=6.0, size=1.0, resolution=2, wrapper=False):
+def surface(*, step=6.0, size=1.0, resolution=2):
     bpy.ops.wm.read_factory_settings(use_empty=True)
     group = CUTOUT_BUILDERS["DEPTH_SOLID"]()
     # Two columns with a complete depth jump along their common boundary.
@@ -70,8 +70,6 @@ def surface(*, step=6.0, size=1.0, resolution=2, wrapper=False):
         ("Boundary Smooth", 0),
     ):
         set_value(name, value)
-    if wrapper:
-        set_value("Cleanup Threshold", 0.0)
     return obj, set_value