fix(files): detect CSV dialect before parsing

dev/test_openwebui_filters.py

@@ -139,6 +139,8 @@ class StabilityGuardTests(unittest.IsolatedAsyncioTestCase):
             ["execute_code"],
         )
         self.assertIn("private table rule", result["messages"][0]["content"])
+        self.assertIn("sep=None", result["messages"][0]["content"])
+        self.assertIn("delimiter", result["messages"][0]["content"])
 
     async def test_private_csv_is_detected_from_user_text_without_metadata(self):
         body = {