StandardErrorResponse

Standardized error envelope emitted by sendErrorResponse and its helpers
(sendValidationError, sendNotFoundError, sendUnauthorizedError,
sendForbiddenError, sendConflictError, sendBadRequestError,
sendInternalServerError).

{
    "success": false,
    "error": {
        "code": "validation_failed",
        "message": "Request validation failed",
        "details": "string"
    },
    "timestamp": 1767225600000
}