fix(api): load multer types for avatar upload typecheck

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/src/auth/auth.service.ts

@@ -19,6 +19,8 @@ import type {
   SubscriptionSummaryDto,
 } from '@mento/shared';
 import { Prisma } from '@prisma/client';
+/** Ensures Express.Multer.File augmentation is loaded for saveAvatar. */
+import type {} from 'multer';
 import { PrismaService } from '../prisma/prisma.service';
 import { SmsService } from '../common/sms.service';
 import { LocalFileStorage } from '../storage/local-file.storage';