complete new audit system

backend/src/services/invoice.service.ts

@@ -1,9 +1,8 @@
-import { PrismaClient, InvoiceType } from '@prisma/client';
+import { InvoiceType } from '@prisma/client';
+import prisma from '../lib/prisma.js';
 import fs from 'fs';
 import path from 'path';
 
-const prisma = new PrismaClient();
-
 export interface CreateInvoiceData {
   invoiceDate: Date;
   invoiceType: InvoiceType;