fix: move pytest.importorskip below pytest import in skip-guarded tests

The original PR placed 'pwd = pytest.importorskip("pwd")' on line 4
but 'import pytest' on line 9 — NameError on module load. Same for
test_file_sync_back.py. Plus, the in-function 'pwd = pytest.importorskip'
calls in test_auto_detected_root_is_rejected confused Python's scope
analysis (later 'import pytest' made pytest local everywhere in the
function) and caused UnboundLocalError. Drop the now-redundant
in-function importorskip calls and rely on the module-level guard.

tests/tools/test_file_sync_back.py

@@ -1,6 +1,5 @@
 """Tests for FileSyncManager.sync_back() — pull remote changes to host."""
 
-fcntl = pytest.importorskip("fcntl")
 import io
 import logging
 import os
@@ -12,6 +11,8 @@ from unittest.mock import MagicMock, call, patch
 
 import pytest
 
+fcntl = pytest.importorskip("fcntl")
+
 from tools.environments.file_sync import (
     FileSyncManager,
     _sha256_file,