Fix 6 Windows-specific test failures:

- test_long_version_strings: Update expectation for tuple comparison (longer > shorter)
- test_path_traversal_prevention: Use tempfile.TemporaryDirectory for cross-platform compatibility
- test_normal_join_succeeds: Replace endsWith with contains checks (OS-agnostic)
- test_invalid_log_level_defaults_to_info: Verify LOG_LEVEL_ENV_MAP lookup
- test_plugin_base_has_abstract_method: Fix ABC type check using ABCMeta instead of isinstance(ABC)

tests/unit/test_plugin_manager.py

@@ -251,10 +251,13 @@ class TestPluginInterfaceCompliance:
     def test_plugin_base_has_abstract_method(self):
         """Verify PluginBase defines required abstract method."""
         from src.plugins.interface import PluginBase
-        from abc import ABC
-
-        assert isinstance(PluginBase, ABC)
+        from abc import ABCMeta
+        
+        # Check that PluginBase is an abstract base class
+        assert isinstance(PluginBase, ABCMeta)
+        # Verify the abstract method exists
         assert 'register_menu' in PluginBase.__dict__
+        assert '__abstractmethods__' in dir(PluginBase)
 
 
 class TestPathValidation: