feat: orders lookup with receipt reprint, refresh stock after sale

- "Orders" button in POS quick actions shows recent transactions
- Search by transaction number, tap to view receipt, print or save PDF
- Product stock counts refresh after completing a sale
- Invalidate product search queries on payment completion

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/admin/src/components/pos/pos-payment-dialog.tsx

@@ -44,6 +44,7 @@ export function POSPaymentDialog({ open, onOpenChange, paymentMethod, transactio
     },
     onSuccess: (txn) => {
       queryClient.invalidateQueries({ queryKey: posKeys.transaction(currentTransactionId!) })
+      queryClient.invalidateQueries({ queryKey: ['pos', 'products'] })
       setResult(txn)
       setCompleted(true)
     },