feat: logo links to home/dashboard

frontend/src/App.module.css

@@ -27,6 +27,12 @@
   display: flex;
   align-items: center;
   gap: 10px;
+  text-decoration: none;
+  color: inherit;
+}
+
+.logoExtra {
+  margin-left: 8px;
 }
 
 .logoImg {

frontend/src/App.tsx

@@ -93,7 +93,7 @@ export default function App() {
     <div className={styles.app}>
       <header className={styles.header}>
         <div className={styles.headerInner}>
-          <div className={styles.logo}>
+          <NavLink to="/" className={styles.logo}>
             <img
               src="/assets/wm2026-trophy.svg"
               alt="FIFA WM 2026"
@@ -103,6 +103,8 @@ export default function App() {
               <span className={styles.logoText}>Tippspiel</span>
               <span className={styles.logoSub}>FIFA World Cup 2026</span>
             </div>
+          </NavLink>
+          <div className={styles.logoExtra}>
             {IS_DEV && (
               <span className={styles.devBadge}>DEV · User {devUser}</span>
             )}