feat: enhance CORS configuration and implement throttling for API endpoints; add admin role checks in controllers

backend/src/receipt-import/receipt-import.controller.ts

@@ -3,7 +3,6 @@ import {
   Post,
   Request,
   UploadedFile,
-  UseGuards,
   UseInterceptors,
   BadRequestException,
 } from '@nestjs/common';
@@ -12,7 +11,6 @@ import { FileInterceptor } from '@nestjs/platform-express';
 import { memoryStorage } from 'multer';
 import { ReceiptImportService } from './receipt-import.service';
 import { ParsedReceiptItem } from './dto/parsed-receipt-item.dto';
-import { JwtAuthGuard } from '../auth/jwt-auth.guard';
 
 const ALLOWED_MIMES = [
   'image/jpeg',
@@ -29,7 +27,6 @@ export class ReceiptImportController {
 
   @Post()
   @Throttle({ default: { ttl: 60_000, limit: 20 } })
-  @UseGuards(JwtAuthGuard)
   @UseInterceptors(
     FileInterceptor('file', {
       storage: memoryStorage(),