feat(banking): add cost centres and VAT to account allocations

backend/src/mcp/statementAllocations.ts

@@ -1,3 +1,5 @@
+import { normalizeBankAllocationDetails } from "../modules/bank-allocation-details"
+
 const hasValue = (value: unknown) => value !== null && value !== undefined && value !== ""
 
 const stringArg = (args: Record<string, unknown>, key: string) => {
@@ -110,6 +112,10 @@ export const prepareStatementAllocationInput = (args: Record<string, unknown>) =
         if (hasInvoice) payload.manualInvoiceSide = manualInvoiceSide
     }
 
+    const details = normalizeBankAllocationDetails({ ...payload, costcentre: args.costcentre })
+    if (args.costcentre !== undefined) payload.costcentre = details.costcentre
+    if (args.datevTaxKey !== undefined) payload.datevTaxKey = details.datevTaxKey
+
     if (bookingMode === "expense") return payload
 
     const depreciationMonths = requiredNumber(args, "depreciationMonths")