v0.4.9a — box art opens full size, a third splash card, and a scoped footer claim

Splash page only: the box art thumbnail opens a full-size lightbox on click, a
new "Play multiplayer" (coming soon) card balances the bottom row to three
cards, and the footer's "runs entirely in your browser" claim is now scoped
to solitaire.

src/web/splash.ts

@@ -7,3 +7,22 @@ if (ties) {
   }
   ties.innerHTML = out;
 }
+
+/** Clicking the box art opens it full size, since the thumbnail is too small to read. */
+const heroImage = document.getElementById('hero-image');
+const lightbox = document.getElementById('lightbox');
+if (heroImage && lightbox) {
+  const open = () => { lightbox.hidden = false; };
+  const close = () => { lightbox.hidden = true; };
+  heroImage.addEventListener('click', open);
+  heroImage.addEventListener('keydown', (e) => {
+    if (e instanceof KeyboardEvent && (e.key === 'Enter' || e.key === ' ')) {
+      e.preventDefault();
+      open();
+    }
+  });
+  lightbox.addEventListener('click', close);
+  document.addEventListener('keydown', (e) => {
+    if (e instanceof KeyboardEvent && e.key === 'Escape') close();
+  });
+}