feat: choose which cart items to pay, with a thumbnail of each

Each cart item has a checkbox and a thumbnail of its first file (or its
extension when there is none). Only checked items are priced, quoted,
uploaded and paid; an unchecked item stays in the cart, dimmed, for a later
order, and stays there after the others are paid. The header count is the
whole cart; the summary counts what is being paid.

Also removes the "A conta nasce aqui…" and "Carrinho salvo neste
navegador…" texts.

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

web/checkout.js

@@ -15,7 +15,7 @@
   let quotedCart = localStorage.getItem('dtf-quote-cart');
   let refreshVersion = 0;
   function cartSnapshot() {
-    const items=[...pedido,...(itemAtual?[itemAtual]:[])];
+    const items=itensAPagar();
     return JSON.stringify({customer:cliente,delivery:entrega,items:items.map(item=>({
       mode:item.modo,metres:item.metros,grade:item.nota,production:item.production,
       quality:item.qualityStatus,
@@ -127,7 +127,7 @@
     arquivos.forEach(f=>enviar(f).catch(()=>{}));
     pintaEnvio();
   }
-  const arquivosDoCarrinho=()=>[...pedido,...(busy&&itemAtual?[itemAtual]:[])].flatMap(it=>it.localFiles||[]);
+  const arquivosDoCarrinho=()=>[...pedido.filter(it=>it.marcado!==false),...(busy&&itemAtual?[itemAtual]:[])].flatMap(it=>it.localFiles||[]);
   const gb=n=>(n/1073741824).toLocaleString('pt-BR',{maximumFractionDigits:1})+' GB';
   const mb=n=>n>=1073741824 ? gb(n) : Math.round(n/1048576)+' MB';
   // Where the uploads stand, and roughly how long is left from the recent speed.
@@ -208,7 +208,7 @@
   // The cart's package: billed metres and value. The charged freight is
   // quoted again by the server from the approved items.
   const pacote = () => {
-    const items=[...pedido,...(itemAtual?[itemAtual]:[])];
+    const items=itensAPagar();
     return {metres:items.reduce((t,it)=>t+(it.cob||0),0), cents:Math.round(items.reduce((t,it)=>t+(it.total||0),0)*100)};
   };
   let freightQuoted = null;
@@ -247,7 +247,7 @@
     if (!clienteOk() || !entrega.cotado) return;
     if (!enderecoOk()) return message('Preencha o endereço de entrega.');
     if (!cartPodeEnviar()) return message('Revise a qualidade e confirme a ressalva de cada item antes de enviar o pedido.');
-    const cart = [...pedido,...(itemAtual?[itemAtual]:[])];
+    const cart = itensAPagar();
     if (!cart.length) return message('Adicione um item ao pedido.');
     const initialCart=cartSnapshot();
     busy = true;
@@ -333,8 +333,7 @@
           event.target.disabled=true;
           try {
             const order=await api('/orders/dev-paid',{quote_id:draftId});
-            pedido=[]; itemAtual=null; limpaPaineis();
-            await window.dtfClearCart?.();
+            await pagos();
             message('Pedido #'+order.number+' criado e disponível no Kanban.');
             await refresh();
           } catch(error) { message(error.message); event.target.disabled=false; }
@@ -360,8 +359,7 @@
         const quote=await api('/quotes/'+draftId);
         if (quote.status==='paid') {
           clearInterval(waitTimer);
-          pedido=[]; itemAtual=null; limpaPaineis();
-          await window.dtfClearCart?.();
+          await pagos();
           await refresh();
         } else if (quote.payment?.status==='rejected') {
           // Refused after the bank's confirmation or the provider's review.
@@ -397,6 +395,11 @@
     actions.append(box);
   }
   const cartOk=()=>!!quotedCart && quotedCart===cartSnapshot();
+  // What was paid leaves the cart; unchecked items stay for another order.
+  async function pagos() {
+    pedido=pedido.filter(it=>it.marcado===false); itemAtual=null; limpaPaineis();
+    if (pedido.length) pintaPedido(); else await window.dtfClearCart?.();
+  }
 
   // Paying: card (the default, paid on this page) or PIX (paid on its own page).
   async function escolhaPagamento(quote, version) {