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_inventory.py

@@ -94,7 +94,7 @@ def test_saved_parameter_descriptions_match_definitions():
                 thickness = next(item for item in sockets if item.name == "Thickness")
                 direction = next(item for item in sockets if item.name == "Depth Direction")
                 offset = next(item for item in sockets if item.name == "Depth Offset")
-                assert offset.default_value == pytest.approx(1.0)
+                assert offset.default_value == pytest.approx(0.0)
                 assert (offset.min_value, offset.max_value) == (-10.0, 10.0)
                 assert offset.subtype == "DISTANCE"
                 assert direction.parent == thickness.parent == offset.parent