feat(drafts): two-button create (Vytvořit / Uložit koncept) + draft finalize UX across offers/invoices/issued-orders

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

src/admin/lib/documentStatus.ts

@@ -75,6 +75,15 @@ export const RECEIVED_INVOICE_STATUS: Record<string, StatusMeta> = {
   paid: { label: "Uhrazena", color: "success" },
 };
 
+/**
+ * Display label for a document's official number. Drafts (deferred numbering)
+ * have a NULL/empty number until they are finalized — show "Koncept" instead
+ * of an empty/`null` heading.
+ */
+export function documentNumberLabel(num: string | null | undefined): string {
+  return num && String(num).trim() ? String(num) : "Koncept";
+}
+
 /** Label with a safe fallback for an unknown/empty key. */
 export const statusLabel = (
   m: Record<string, StatusMeta>,