fix: make TOTP replay protection test more robust

Ensure auth file is properly initialized before testing replay protection.
Add better error message to diagnose failures.

dashboard/backend/tests/unit/test_auth.py

@@ -245,11 +245,21 @@ class TestTOTP:
     def test_verify_totp_replay_protection(self, mock_config, temp_auth_file, sample_totp_secret):
         """Test that same TOTP code cannot be used twice."""
         save_totp_secret(sample_totp_secret)
+
+        # Ensure auth file is properly initialized with last_totp_ts
+        import json
+        with open(temp_auth_file, 'r') as f:
+            data = json.load(f)
+        data['last_totp_ts'] = 0
+        with open(temp_auth_file, 'w') as f:
+            json.dump(data, f)
+
         totp = pyotp.TOTP(sample_totp_secret)
         valid_code = totp.now()
 
         # First use should succeed
-        assert verify_totp(valid_code)
+        result = verify_totp(valid_code)
+        assert result, f"First TOTP verification failed for code {valid_code}"
 
         # Second use of same code should fail (replay protection)
         assert not verify_totp(valid_code)