Add tests and implement boundary smoothing and cutout functionality

- Introduced tests for boundary smoothing in `test_boundary_smoothing.py`, verifying that smoothing reduces stair-step artifacts while preserving boundary integrity.
- Added tests for cutout boundary behavior in `test_cutout_boundary.py`, ensuring proper handling of boundary triangles and normal blending.
- Created `test_temporary_attributes.py` to check the cleanup of temporary attributes across depth modifier branches, ensuring no warnings are raised.
- Implemented point culling functionality in `test_validity.py`, confirming that invalid points are removed without affecting adjacent geometry.
- Developed boundary smoothing logic in `boundary_smoothing.py`, allowing for depth smoothing while maintaining edge integrity.
- Added cutout boundary management in `cutout_boundary.py`, including functions for removing boundary triangles and tapering thickness profiles.
- Implemented validity checks in `validity.py` to ensure proper deletion of invalid vertices and associated wire edges.

tests/tools/test_pack.py

@@ -131,7 +131,6 @@ class ExtensionPackagingTest(unittest.TestCase):
                 self.assertIn("server/geometry/panorama.py", names)
                 self.assertIn("server/geometry/depth_texture.py", names)
                 self.assertIn("server/geometry/prediction_artifacts.py", names)
-                self.assertIn("server/geometry/edge_depth.py", names)
                 self.assertIn("server/geometry/normal_texture.py", names)
                 self.assertNotIn(
                     "server/geometry/generate_geometry_and_normal.py", names