refactor(auth): replace anchor navigation links with Button components and improve auth page styling

src/features/auth/pages/RegisterPage.client.js

@@ -208,6 +208,7 @@ export default function RegisterPage({ onSubmit, onNavigate, currentUser = null
         <Button
           type="submit"
           variant="primary"
+          size="lg"
           loading={isLoading}
           disabled={!!success || !!currentUser || !isFormValid()}
           className="w-full mt-2"
@@ -216,18 +217,15 @@ export default function RegisterPage({ onSubmit, onNavigate, currentUser = null
         </Button>
       </form>
 
-      <div className={`mt-6 text-center transition-opacity duration-200 ${currentUser ? 'opacity-50 pointer-events-none' : ''}`}>
-        <a
-          href="#"
-          onClick={(e) => {
-            e.preventDefault();
-            if (!currentUser) onNavigate('login');
-          }}
-          className="group flex items-center justify-center gap-2"
+      <div className={`mt-6 flex justify-center transition-opacity duration-200 ${currentUser ? 'opacity-50 pointer-events-none' : ''}`}>
+        <Button
+          type="button"
+          variant="ghost"
+          disabled={!!currentUser}
+          onClick={() => { if (!currentUser) onNavigate('login'); }}
         >
-          <span className="text-sm text-neutral-600 dark:text-neutral-400">Vous avez déjà un compte ? </span>
-          <span className="text-sm text-neutral-900 group-hover:text-neutral-600 font-medium transition-colors duration-200 dark:text-white dark:group-hover:text-neutral-300">Se connecter</span>
-        </a>
+          Vous avez déjà un compte ? Se connecter
+        </Button>
       </div>
     </Card>
   );