test(work_plane): drop unused imports

tempfile, Path, and unittest.mock.patch were imported but unused.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_work_plane.py

@@ -2,9 +2,6 @@
 from __future__ import annotations
 
 import json
-import tempfile
-from pathlib import Path
-from unittest.mock import patch
 
 import numpy as np
 import pytest