refactor: rename POST endpoint to 'update' for clarity in AdsController

apps/box-mgnt-api/src/mgnt-backend/feature/ads/ads.controller.ts

@@ -68,7 +68,7 @@ export class AdsController {
     return this.service.create(dto);
   }
 
-  @Post()
+  @Post('update')
   @ApiOperation({
     summary:
       'Update an ad (adType updates honored, legacy adsModuleId is resolved)',