fix: update Prisma client configuration and test files for Prisma 7.x compatibility

src/__tests__/e2e/epic1-auth-logout.test.ts

@@ -11,9 +11,8 @@
  */
 
 import { test, expect } from '@playwright/test';
-import { PrismaClient } from '@prisma/client';
+import { prisma } from '@/lib/prisma';
 
-const prisma = new PrismaClient();
 
 function getTestCredentials() {
   const timestamp = Date.now();