feat(drafts): show Koncept for null numbers in lists + fix filtered empty-state

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/pages/IssuedOrders.tsx

@@ -33,6 +33,7 @@ import {
   statusLabel,
   statusColor,
   statusOptions,
+  documentNumberLabel,
 } from "../lib/documentStatus";
 
 const API_BASE = "/api/admin";
@@ -206,7 +207,7 @@ export default function IssuedOrders({ month, year }: IssuedOrdersProps) {
             "&:hover": { textDecoration: "underline" },
           }}
         >
-          {o.po_number || "—"}
+          {documentNumberLabel(o.po_number)}
         </Box>
       ),
     },