feat(web): inset token silhouette by 2px

Pass a negative offset through traceImage so the traced token shape
sits slightly inside the artwork, hiding the anti-aliased fringe.

apps/web/src/components/viewers/TokenViewer.tsx

@@ -14,6 +14,9 @@ import { assetUrl } from './assetUrl';
 
 const TOKEN_SIZE = 1.8;
 
+/** How far (in trace pixels) the token silhouette is inset from the artwork. */
+const TRACE_INSET = 2;
+
 /**
  * A token: a short extruded shape with the texture on its top face. Uses
  * `CustomImage.ImageURL` (falling back to `ImageSecondaryURL`), with a neutral
@@ -46,7 +49,7 @@ function TokenMesh({ url, thickness }: { url?: string; thickness: number }) {
     let cancelled = false;
     setTrace(null);
     if (!url) return;
-    traceImage(url, 'alpha')
+    traceImage(url, 'alpha', -TRACE_INSET)
       .then((result) => {
         if (!cancelled && result.shape) {
           setTrace({