Transactions - Adding `interbank_code` in the response

We're now returning the interbank_code attribute in the response of the Transactions endpoints, offering more context about transaction types and origins.

Impacted endpoints:

• List transactions
• Retrieve a transaction
• Create a transaction
• Update a transaction

This is a non-breaking change – existing integrations will continue to work without modification. The new field is additional and does not affect the existing response structures.