Add ruff rule for empty line with trailing whitespace.

tests-unit/server/services/file_service_test.py

@@ -20,9 +20,9 @@ def test_list_files_valid_directory(file_service, mock_file_system_ops):
         {"name": "file1.txt", "path": "file1.txt", "type": "file", "size": 100},
         {"name": "dir1", "path": "dir1", "type": "directory"}
     ]
-    
+
     result = file_service.list_files("models")
-    
+
     assert len(result) == 2
     assert result[0]["name"] == "file1.txt"
     assert result[1]["name"] == "dir1"
@@ -35,9 +35,9 @@ def test_list_files_invalid_directory(file_service):
 
 def test_list_files_empty_directory(file_service, mock_file_system_ops):
     mock_file_system_ops.walk_directory.return_value = []
-    
+
     result = file_service.list_files("models")
-    
+
     assert len(result) == 0
     mock_file_system_ops.walk_directory.assert_called_once_with("/path/to/models")
 
@@ -46,9 +46,9 @@ def test_list_files_all_allowed_directories(file_service, mock_file_system_ops,
     mock_file_system_ops.walk_directory.return_value = [
         {"name": f"file_{directory_key}.txt", "path": f"file_{directory_key}.txt", "type": "file", "size": 100}
     ]
-    
+
     result = file_service.list_files(directory_key)
-    
+
     assert len(result) == 1
     assert result[0]["name"] == f"file_{directory_key}.txt"
-    mock_file_system_ops.walk_directory.assert_called_once_with(f"/path/to/{directory_key}")
+    mock_file_system_ops.walk_directory.assert_called_once_with(f"/path/to/{directory_key}")