get_payer_total currently requires iterating all payments. Consider exposing a dedicated storage key per (invoice_id, payer) pair for O(1) lookup.
Impact: Reduces compute cost for invoices with many payers, relevant for crowdfunded invoice use cases on Stellar.
get_payer_totalcurrently requires iterating all payments. Consider exposing a dedicated storage key per (invoice_id, payer) pair for O(1) lookup.Impact: Reduces compute cost for invoices with many payers, relevant for crowdfunded invoice use cases on Stellar.