feat: rename invoice (RE-) to order confirmation (BE-) throughout the application

shop/components/admin/orders-table.tsx

@@ -182,7 +182,7 @@ export function OrdersTable({ initialOrders }: OrdersTableProps) {
                           </Button>
                         </div>
                       ) : (
-                        <span className="text-xs text-slate-500 italic">Keine Rechnung</span>
+                        <span className="text-xs text-slate-500 italic">Keine Bestätigung</span>
                       )}
                     </TableCell>
                   </TableRow>

shop/components/invoice-pdf.tsx

@@ -117,10 +117,10 @@ export const InvoicePDF = ({ order, orderSnapshot, customer }: any) => {
           </View>
         </View>
 
-        <Text style={styles.title}>Bestellbestätigung / Rechnung</Text>
+        <Text style={styles.title}>Bestellbestätigung</Text>
 
         <View style={styles.section}>
-          <Text style={styles.label}>Rechnungsempfänger</Text>
+          <Text style={styles.label}>Besteller / Kunde</Text>
           <Text>{customer.company_name}</Text>
           <Text>{customer.first_name} {customer.last_name}</Text>
           <Text>{customer.address}</Text>