Parse large Excel imports asynchronously to avoid gateway 502 timeouts.

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

apps/api/src/activities/activities.controller.ts

@@ -113,6 +113,14 @@ export class ActivitiesController {
     return this.excelService.prepare(user, file, mapping);
   }
 
+  @Get('import/prepare/:sessionId')
+  importPrepareStatus(
+    @CurrentUser() user: Actor,
+    @Param('sessionId') sessionId: string,
+  ) {
+    return this.excelService.prepareStatus(user, sessionId);
+  }
+
   @Post('import')
   @UseInterceptors(excelUpload)
   import(