fix(site): size the particle canvas to the viewport

The canvas sets width and height attributes scaled by devicePixelRatio.
Those give the element a specified size that inset: 0 cannot shrink, so on
a 2x display the box was twice the viewport and the dots covered only the
top-left quadrant. Percentages resolve against the fixed containing block
and, unlike 100vw, exclude the scrollbar gutter.

Author: elkaix

apps/site/src/components/ParticleField.vue

@@ -151,6 +151,8 @@ onUnmounted(() => {
   position: fixed;
   z-index: -1;
   inset: 0;
+  width: 100%;
+  height: 100%;
   pointer-events: none;
 }
 </style>