feat: add custom je favicon

SVG icon matching the header logo mark (dark tile, "je", emerald dot),
with a multi-size favicon.ico fallback and an apple-touch-icon.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

components/Layout.js

@@ -16,7 +16,10 @@ export default function Layout({ children, title, description }) {
         <meta property="og:title" content={pageTitle} />
         <meta property="og:description" content={pageDescription} />
         <meta property="og:type" content="website" />
-        <link rel="icon" href="/favicon.ico" />
+        <link rel="icon" href="/favicon.ico" sizes="48x48" />
+        <link rel="icon" href="/icon.svg" type="image/svg+xml" />
+        <link rel="apple-touch-icon" href="/apple-touch-icon.png" />
+        <meta name="theme-color" content="#0c0a09" />
       </Head>
 
       <Header />