- test_auto_topup: use MagicMock (not Mock) so the DB context manager works in
  auto_charge; mock _get_or_create_customer and return a Stripe-object-shaped
  PaymentIntent (attribute access, not dict); replace the retry-logic test's
  bare AsyncMock with a small stateful fake session so record_auto_topup_attempt
  actually transitions auto_topup_enabled to False after 3 failures.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>