fix(badges): add missing updated_on column to CSV export

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/routes/events/[event_id]/(badges)/badges/reports/reports_badge_export.svelte

@@ -135,6 +135,7 @@ const COLUMNS: ColDef[] = [
     { header: 'print_last_datetime', value: (b) => fmt_dt(b.print_last_datetime) },
     { header: 'print_count', value: (b) => b.print_count ?? 0 },
     { header: 'created_on', value: (b) => fmt_dt(b.created_on) },
+    { header: 'updated_on', value: (b) => fmt_dt(b.updated_on) },
     { header: 'event_badge_id', value: (b) => b.event_badge_id ?? '' }
 ];