Vendor the landing cloud texture locally instead of fetching a CDN.

drei's volumetric clouds fetch their puff sprite from a GitHub CDN at runtime.
Save that exact image to frontend/public/cloud.png and point <Clouds> at it, so
the landing page never reaches out to any external site while keeping the
original cloud look.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/components/landing/SceneCanvas.tsx

@@ -105,6 +105,11 @@ function SceneLights() {
   );
 }
 
+// drei's volumetric clouds use a soft "puff" sprite. By default drei fetches it
+// from a GitHub CDN at runtime; we vendor that exact image into /public instead
+// (see public/cloud.png) so the page never reaches out to any external website.
+const CLOUD_TEXTURE = '/cloud.png';
+
 function CloudLayer({ clouds, segments }: { clouds: number; segments: number }) {
   const group = useRef<THREE.Group>(null);
   const specs = useMemo(() => makeCloudField(clouds), [clouds]);
@@ -121,7 +126,7 @@ function CloudLayer({ clouds, segments }: { clouds: number; segments: number })
 
   return (
     <group ref={group}>
-      <Clouds material={THREE.MeshLambertMaterial} limit={clouds * segments + 64} frustumCulled={false}>
+      <Clouds texture={CLOUD_TEXTURE} material={THREE.MeshLambertMaterial} limit={clouds * segments + 64} frustumCulled={false}>
         {specs.map((c, i) => (
           <Cloud
             key={i}