feat: icons in the header and on the Montagem controls

The header's search, account and cart get icons, with the item count on the
cart instead of "Carrinho (N)"; on phones only the icons show. The upload
zone, remove, rotate and mirror buttons used Unicode symbols that look
different, or are missing, depending on the system's fonts; they are now
Lucide icons (ISC licence) drawn inline, so nothing new is loaded and the
CSP is unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/site-cart.js

@@ -61,7 +61,8 @@ function pintaPedido(){
     : 'Ir para o pagamento';
   $('bPagar').disabled = !cartPodeEnviar() || !entrega.cotado || !clienteOk() || !enderecoOk();
   if(pedido.length || itemAtual) $('carr').classList.add('on');
-  if($('cartLink')) $('cartLink').textContent='Carrinho ('+n+')';
+  if($('cartN')){ $('cartN').textContent=n>99?'99+':n; $('cartN').hidden=!n;
+    $('cartLink').setAttribute('aria-label','Carrinho, '+n+(n===1?' item':' itens')); }
   window.dispatchEvent(new Event('dtf-cart-changed'));
 }