feat(follow): add feed links, following page and tile (#52, #51)

Feed links go to the game and to the profile view of that game.
Add /following page, nav item and an opt-in Following tile.
Games not in your library show a catalog view with an add button.

src/components/AddGamePanel.jsx

@@ -22,11 +22,14 @@ import {useCurrentUserContext} from '../context/CurrentUserContext.jsx';
 /**
  * Search IGDB and add a game the user owns outside Steam, e.g. on PlayStation or Switch; or check several and review
  * them on the import page.
+ *
+ * @param onAdded called with the new appid before the navigation, for a page that shows the same address
+ * @param initialQuery the search text to start with, e.g. the name of a game seen elsewhere
  */
-export default function AddGamePanel({onClose}) {
+export default function AddGamePanel({onClose, onAdded, initialQuery = ''}) {
     const {t} = useTranslation();
     const navigate = useNavigate();
-    const [query, setQuery] = useState('');
+    const [query, setQuery] = useState(initialQuery);
     const [picked, setPicked] = useState(null);
     // igdbId -> hit, over several searches.
     const [selected, setSelected] = useState(() => new Map());
@@ -62,7 +65,8 @@ export default function AddGamePanel({onClose}) {
             </div>
 
             {picked ? (
-                <AddForm hit={picked} favorite={favorite} onBack={() => setPicked(null)} navigate={navigate}/>
+                <AddForm hit={picked} favorite={favorite} onBack={() => setPicked(null)} navigate={navigate}
+                         onAdded={onAdded}/>
             ) : (
                 <>
                     <p className="text-sm text-muted-foreground">{t('MANUAL_GAME.ADD_HINT')}</p>
@@ -82,7 +86,7 @@ export default function AddGamePanel({onClose}) {
     );
 }
 
-function AddForm({hit, favorite, onBack, navigate}) {
+function AddForm({hit, favorite, onBack, navigate, onAdded}) {
     const {t} = useTranslation();
     const [platform, setPlatform] = useState(() => preselectPlatform(null, hit.platforms, favorite));
     // The favorite can arrive after the pick; it fills only a platform the user has not picked yet.
@@ -113,6 +117,7 @@ function AddForm({hit, favorite, onBack, navigate}) {
             const {appid} = await response.json();
             toast.success(t('MANUAL_GAME.ADDED', {name: hit.name}));
             check(appid, {status, tell: true});
+            onAdded?.(appid);
             navigate(`/library/${appid}`);
         } catch (err) {
             console.error('add game error:', err);