feat(home): replace text logo with WikiRush image

app/components/HomeScreen.tsx

@@ -1,5 +1,6 @@
 "use client";
 
+import Image from "next/image";
 import type { Session } from "next-auth";
 
 type HomeScreenProps = {
@@ -39,10 +40,7 @@ export function HomeScreen({
       </div>
 
       <div className="home-hero">
-        <div className="home-logo">
-          <span className="logo-wiki">Wiki</span>
-          <span className="logo-race">Rush</span>
-        </div>
+        <Image src="/wikirush.png" alt="WikiRush" width={320} height={320} className="home-logo-img" priority />
         <p className="home-subtitle">
           Navigue entre les articles Wikipedia pour atteindre la cible en premier !
         </p>

app/globals.css

@@ -186,16 +186,13 @@ body {
   text-align: center;
 }
 
-.home-logo {
-  font-size: clamp(42px, 10vw, 72px);
-  font-weight: 900;
-  letter-spacing: -2px;
-  line-height: 1;
+.home-logo-img {
+  width: clamp(180px, 50vw, 280px);
+  height: auto;
+  display: block;
+  margin: 0 auto;
 }
 
-.logo-wiki { color: var(--text); }
-.logo-race { color: var(--accent); }
-
 .home-subtitle {
   margin-top: 12px;
   color: var(--text-muted);