feat(tasks): group "Alle Aufgaben" by task list by default

Tasks without a list come first, then the lists in tab order. Single
lists keep no grouping by default and do not offer it. The open task
list, view and grouping, like the open shopping list, are now
remembered per device instead of per tab.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/lists/SharedListsView.tsx

@@ -11,7 +11,7 @@ import {
 } from 'lucide-react';
 import { ListItem, SharedList, Team, User, WSMessage } from '../../lib/types';
 import { api, triggerHaptic, createRealtimeConnection } from '../../lib/api';
-import { readViewSession, writeViewSession } from '../../lib/viewSession';
+import { readViewMemory, writeViewMemory } from '../../lib/viewSession';
 import { OFFLINE_ITEM_PREFIX, pendingListItems } from '../../lib/offline';
 import { UnifiedShareModal } from '../../components/UnifiedShareModal';
 import { AvatarStack, AvatarPerson } from '../../components/AvatarStack';
@@ -91,12 +91,12 @@ export function deduplicateItems(items: ListItem[]): ListItem[] {
 export const SharedListsView: React.FC<SharedListsViewProps> = ({ onRefreshGlobal, currentUser, initialListId }) => {
   const { setGroups, setPrimaryAction } = useMobileActions();
   const [lists, setLists] = useState<SharedList[]>([]);
-  // The open list survives switching to other tabs (like the workspace's open note)
+  // The open list is remembered on this device (other tabs of the app, new tab, restart)
   const [activeListId, setActiveListId] = useState<string>(
-    () => initialListId || readViewSession<{ listId: string }>('lists').listId || ''
+    () => initialListId || readViewMemory<{ listId: string }>('lists').listId || ''
   );
   useEffect(() => {
-    if (activeListId) writeViewSession('lists', { listId: activeListId });
+    if (activeListId) writeViewMemory('lists', { listId: activeListId });
   }, [activeListId]);
 
   useEffect(() => {