fix(packaging): centre the play mark in the desktop icon

The mark's box centred on x=73 of the 64-centred tile, so it sat visibly
right. It now centres x=70, between its box and its centroid, as the
Android and iOS icons already do. icon-256.png and the Windows .ico are
rendered again from the SVG.

images/logo.svg

@@ -26,9 +26,14 @@
   <rect x="12" y="12" width="104" height="100" rx="26" fill="url(#ps-face)"/>
   <rect x="12.5" y="12.5" width="103" height="99" rx="25.5" stroke="#FFFFFF" stroke-opacity="0.2"/>
 
-  <!-- glyph shadow, then the glyph itself -->
-  <g transform="translate(0 3)">
-    <rect width="128" height="128" fill="#2E1596" fill-opacity="0.3" mask="url(#ps-cut)"/>
+  <!-- glyph shadow, then the glyph itself. The mark's box centres on x=73 and
+       its centroid on x=66; it sits at 70 -> 64, between the two, because the
+       box centre reads as too far left and the centroid as too far right. The
+       Android and iOS icons centre it the same way. -->
+  <g transform="translate(-6 0)">
+    <g transform="translate(0 3)">
+      <rect width="128" height="128" fill="#2E1596" fill-opacity="0.3" mask="url(#ps-cut)"/>
+    </g>
+    <rect width="128" height="128" fill="url(#ps-glyph)" mask="url(#ps-cut)"/>
   </g>
-  <rect width="128" height="128" fill="url(#ps-glyph)" mask="url(#ps-cut)"/>
 </svg>