feat: the upload bar says how long is left, not a notice before it

The product page's notice about the upload time is gone. The cart's upload
bar now reads "Enviando seus arquivos · faltam cerca de 6 min", measured
from the upload's own speed (a range from the size for the first seconds),
with a line saying the time depends on the internet and to keep the page
open. The header and the pay button show the same time instead of a
percentage.

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

web/site-flow.js

@@ -29,7 +29,6 @@ function guardaItem(){
   $('foco').classList.remove('on');
   ['qual','prev'].forEach(id=>$(id).classList.remove('on'));
   modo=null; artes=[]; folhas=[]; metros=0; nota=0; montagemCm=0;
-  pintaAvisoEnvio();
   pintaPedido();
   return true;
 }