Cabinet was calling YooKassaService.create_payment() directly, bypassing
PaymentService which saves the payment record to the local database.
When YooKassa webhook arrived, the payment was not found in the DB,
causing payment processing failures.
Now uses PaymentService.create_yookassa_payment() and
create_yookassa_sbp_payment() consistently with all other payment methods.
Also standardizes metadata key from 'type' to 'purpose' to match bot flow.
Fringg
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