chore: apply ruff auto-fixes and remove dead AST scripts

tests/test_tier4_interceptor.py

@@ -1,6 +1,4 @@
-import pytest
 from unittest.mock import MagicMock, patch
-import subprocess
 from shell_runner import run_powershell
 
 def test_run_powershell_qa_callback_on_failure(vlogger) -> None: