redsys_button 2.1.1

- Create token-protected payment links with a fixed amount and concept.
- Support optional expiration dates and suggested payer email addresses.
- Allow card, Bizum, PayPal, and xPay payment methods.
- Duplicate, cancel, and audit payment requests.
- Prevent simultaneous payment attempts.
- Reopen requests after authenticated rejection or customer cancellation.
- Permanently close requests after a confirmed successful payment.
- Store every attempt in the existing Redsys payment audit history.
- Fix dependency serialization in payment request forms.