feat: accept large JPG and WebP artworks instead of refusing them

Above 150 MB the browser cannot read JPG or WebP in parts, so a large
artwork was refused. It is now measured from its header, graded and priced
with the discount like any other, and placed on the sheet as a full box,
which is exact for JPG. The card says there is no preview and that the team
checks the art before printing.

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

web/site-upload.js

@@ -128,7 +128,9 @@ function medir(a){
     return dimensoesImagem(a.f).then(async d=>{
       if(!d || !(d.w>0) || !(d.h>0)){ a.decodeError=true; return a; }
       a.px=d.w; a.py=d.h; a.prop=d.h/d.w; a.grande=true;
-      if(!/\.png$/i.test(a.f.name)){ a.decodeError='grande'; return a; }
+      // JPG and WebP cannot be read in parts: the art is placed by its
+      // measurements, as a full box, and the team checks it before printing.
+      if(!/\.png$/i.test(a.f.name)){ a.semPrevia=true; return a; }
       a.lendo=0; pintaArtes();
       let mostrado=0;
       const cv=await previaPngGrande(a.f, 1200, p=>{