complete new audit system

backend/src/services/customer.service.ts

@@ -1,10 +1,9 @@
-import { PrismaClient, CustomerType, ContractStatus } from '@prisma/client';
+import { CustomerType, ContractStatus } from '@prisma/client';
+import prisma from '../lib/prisma.js';
 import { generateCustomerNumber, paginate, buildPaginationResponse } from '../utils/helpers.js';
 import fs from 'fs';
 import path from 'path';
 
-const prisma = new PrismaClient();
-
 // Helper zum Löschen von Dateien
 function deleteFileIfExists(filePath: string | null) {
   if (!filePath) return;