refactor(OUT-3874): drop unused TxnTaxDetail from QBInvoiceRowSchema

The create-invoice response no longer reads TxnTaxDetail now that tax is
always sourced from Assembly, so remove the field to stop implying we
consume it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: SandipBajracharya

src/type/dto/intuitAPI.dto.ts

@@ -300,11 +300,6 @@ export const QBInvoiceRowSchema = z.object({
   DueDate: z.string().optional(),
   PrivateNote: z.string().optional(),
   CustomerRef: QBNameValueSchema.optional(),
-  TxnTaxDetail: z
-    .object({
-      TotalTax: z.number(),
-    })
-    .optional(),
 })
 export type QBInvoiceRowType = z.infer<typeof QBInvoiceRowSchema>