Add store-item Excel export/import for bulk price and stock updates.

Dashboard can download grouped product variants and re-upload to update price and stock. Also expose Content-Disposition for downloads and keep related product/customer API docs in sync.

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

src/main.ts

@@ -24,7 +24,9 @@ async function bootstrap() {
     }),
   );
   app.useGlobalInterceptors(new BigIntSerializerInterceptor());
-  app.enableCors();
+  app.enableCors({
+    exposedHeaders: ['Content-Disposition'],
+  });
 
   const port = process.env.PORT ?? 3000;
   await app.listen(port);