Replace hero visual with user-provided reference image

Ariver

2026-06-06 da43ff3d7c2fd1f1b480dbbb05d9502a083b85fc

 docs/index-en.html

@@ -42,7 +42,7 @@
          src="assets/hero-visual.jpg"
          alt="TagLauncher App Grid with stacked 3D window presentation"
          width="1024"
          height="846"
          height="908"
          fetchpriority="high"
          decoding="async">
      </figure>