feat(auth): tell the user when the session expired

Every 401 from Auth or Core now goes through useSessionExpired: the login page
says the session expired and returns to the last page after login. App no
longer removes a token that only the browser clock calls expired, so a backend
401 is the one signal. A 403 on the profile now shows an error instead.

src/pages/GameDetail.jsx

@@ -12,6 +12,7 @@ import BacklogCard from '../components/BacklogCard.jsx';
 import GameCover from '../components/GameCover.jsx';
 import GameStatusBadge from '../components/GameStatusBadge.jsx';
 import {formatPlaytime} from '../utils/games.js';
+import useSessionExpired from '../hooks/useSessionExpired.js';
 
 const formatUnlockedAt = (instant, locale) => {
     if (!instant) return '';
@@ -26,6 +27,7 @@ export default function GameDetail() {
     const {t, i18n} = useTranslation();
     const {appid} = useParams();
     const navigate = useNavigate();
+    const expireSession = useSessionExpired();
 
     const [data, setData] = useState(null);
     const [isLoading, setIsLoading] = useState(true);
@@ -51,8 +53,7 @@ export default function GameDetail() {
                 });
                 if (cancelled) return;
                 if (response.status === 401) {
-                    localStorage.removeItem('tbp_jwt');
-                    navigate('/login');
+                    expireSession();
                     return;
                 }
                 if (response.status === 404) {
@@ -77,7 +78,7 @@ export default function GameDetail() {
         return () => {
             cancelled = true;
         };
-    }, [appid, navigate, t]);
+    }, [appid, navigate, expireSession, t]);
 
     const sortedAchievements = useMemo(() => {
         if (!data?.achievements) return [];