order-details: null item amounts render nothing, not $0.00; qty defaults to 1

Spine-bridged receipts (Amazon shipment notices, eBay) name the goods
without per-item prices — null means 'the mail didn't say', and printing
$0.00 would assert it did.

src/components/order-details.tsx

@@ -99,7 +99,7 @@ export function OrderDetails({
         <ul className="space-y-1.5 mb-3">
           {items.map((it, i) => (
             <li key={i} className="flex gap-2 text-xs items-start">
-              <span className="text-zinc-600 tabular-nums shrink-0">{it.qty}×</span>
+              <span className="text-zinc-600 tabular-nums shrink-0">{it.qty ?? 1}×</span>
               <span className="text-zinc-300 flex-1 min-w-0">
                 {it.description}
                 {it.options && it.options.length > 0 && (
@@ -114,7 +114,12 @@ export function OrderDetails({
                 rating={mine?.rating ?? null}
                 note={mine?.note ?? null}
               />
-              <span className="text-zinc-400 tabular-nums shrink-0">{fmt(Number(it.amount))}</span>
+              {/* Spine-bridged receipts (Amazon shipment notices, eBay) often
+                  name the goods without per-item prices — a null here is "the
+                  mail didn't say", and printing $0.00 would assert it did. */}
+              {it.amount != null && (
+                <span className="text-zinc-400 tabular-nums shrink-0">{fmt(Number(it.amount))}</span>
+              )}
             </li>
           ))}
         </ul>