Charge Webhook Events Renamed to Payment Events

We've renamed the charge.* webhook events to payment.* (payment.failed, payment.succeeded, payment.refund_initiated, payment.refunded, payment.refund_failed, payment.card_verified, payment.authorized, payment.voided). The charge.* names are kept as legacy aliases — both are dispatched for the same event, so existing subscriptions keep working unchanged. New integrations should subscribe to payment.*.