feat: add settlement_type to SalesInvoice model and related DTOs

- Added settlement_type field to SalesInvoice model with ENUM values (CASH, CREDIT, MIXED).
- Updated SalesInvoice aggregate types, input types, and where filters to include settlement_type.
- Modified StatisticsService to calculate credit amounts based on settlement_type.
- Enhanced TspProviderOriginalSendPayloadDto to include settlement_type.
- Updated NamaProvider DTOs and utility functions to handle new settlement_type logic.
- Created migration to add settlement_type column to sales_invoices table and backfill existing records.

src/generated/prisma/internal/prismaNamespaceBrowser.ts

@@ -622,6 +622,7 @@ export const SalesInvoiceScalarFieldEnum = {
   invoice_number: 'invoice_number',
   invoice_date: 'invoice_date',
   type: 'type',
+  settlement_type: 'settlement_type',
   tax_id: 'tax_id',
   notes: 'notes',
   unknown_customer: 'unknown_customer',