Function export_dataset_human 

pub fn export_dataset_human(
    corpus: &str,
    service: &str,
    form: Form<ExportForm>,
    session: Option<AdminSession>,
    pool: &State<DbPool>,
    database_url: &State<DatabaseUrl>,
) -> Result<Redirect, Template>

The human twin of export_dataset: the “Export dataset” form post. Gated by the signed-in AdminSession cookie (anonymous → sign-in); spawns the background export via the shared [start_export] core and redirects to the job’s live-progress page. A failed submit re-renders the form with a friendly message + the values preserved (404 unknown corpus/service, 422 bad grouping / no severity).