[ui] optimisation pour avoir une icone nette (crisp)

prive/themes/spip/images/portfolio-xx.svg

 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" width="64" height="64">
-  <path fill="#fff" d="M8 11h48v42H8z"/>
-  <path fill="#666" d="M56 11H8v42l27.9-27.9c1.2-1.2 3.1-1.2 4.2 0L56 41V11zM2 8c0-1.6 1.3-3 3-3h54c1.6 0 3 1.3 3 3v48c0 1.6-1.3 3-3 3H5c-1.6 0-3-1.3-3-3V8zm18 21c-3.3 0-6-2.7-6-6s2.7-6 6-6 6 2.7 6 6-2.7 6-6 6z" />
+  <path fill="#fff" d="M10 11h46v40H10z"/>
+  <path fill="#666" d="M54 12H10v38l25.6-25c1.1-1.1 2.9-1.1 3.9 0L54 40V12zM4 8c0-1.5.4-2 2-2h52c1.5 0 2 .4 2 2v47c0 1.5-.4 2-2 2H6c-1.5 0-2-.4-2-2V8z"/>
+  <circle fill="#666" cx="20" cy="21" r="5"/>
 </svg>