Reproduces 302-redirect bug observed on prod 2026-05-25 — when supplier
crm.bp-gr.ru POSTs without Accept: application/json, Laravel renders
ValidationException as redirect to /, losing body. Test calls webhook
without Accept header and asserts JSON 422 response. Will fail until
bootstrap/app.php has render(ValidationException) for api/webhook/supplier/*.
Дмитрий