chore(frontend): real ESLint instead of a placeholder; fix hook order (FLAW-19)

eslint.config.js with the recommended JS/TypeScript rules and the React
hooks rules; npm run lint runs ESLint and is part of the image build.
Errors fail the build, the 24 exhaustive-deps findings stay warnings.

It found two real bugs: TaskDetailModal and ManageColumnsModal called
their hooks after 'if (!isOpen) return null', so the hook count changed
whenever the dialog opened or closed. Both are now a thin wrapper plus a
content component. Also removes unused imports and dead code (old task
list share handlers, an unused realtime status, an unused rollup).

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

frontend/src/features/workspace/WorkspaceView.tsx

@@ -18,15 +18,11 @@ import {
   ExternalLink,
   Sparkles,
   ArrowLeft,
-  CheckSquare,
   PanelLeftClose,
   PanelLeftOpen,
-  ChevronLeft,
-  Radio,
   Clock,
   AlertTriangle,
   Loader2,
-  Lock,
 } from 'lucide-react';
 import {
   Document,
@@ -44,10 +40,6 @@ import {
   api,
   onWebSocketMessage,
   triggerHaptic,
-  onRealtimeStatus,
-  isRealtimeConnected,
-  getRealtimeTransport,
-  RealtimeTransport,
 } from '../../lib/api';
 import { UnifiedShareModal } from '../../components/UnifiedShareModal';
 import { FormSheet } from '../../components/FormSheet';
@@ -347,7 +339,6 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
   const [newFolderCoords, setNewFolderCoords] = useState<{ x: number; y: number } | null>(null);
   const [newFolderParentPath, setNewFolderParentPath] = useState<string>('');
   const [newFolderName, setNewFolderName] = useState<string>('');
-  const [newFolderIsShared, setNewFolderIsShared] = useState<boolean>(false);
 
   const handleOpenNewFolder = (parentPath = '', e?: React.MouseEvent) => {
     setNewFolderParentPath(parentPath);
@@ -381,19 +372,9 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     });
   }, []);
 
-  // Realtime connection status for top header indicator (identical to SharedListsView)
-  const [realtimeConnected, setRealtimeConnected] = useState<boolean>(() => isRealtimeConnected());
-  const [realtimeTransport, setRealtimeTransport] = useState<RealtimeTransport>(() => getRealtimeTransport());
   const [docSaveStatus, setDocSaveStatus] = useState<DocSaveStatus>('saved');
   const [docSaveError, setDocSaveError] = useState<string | null>(null);
 
-  useEffect(() => {
-    const unsub = onRealtimeStatus((connected, transport) => {
-      setRealtimeConnected(connected);
-      setRealtimeTransport(transport);
-    });
-    return unsub;
-  }, []);
 
   // Drag and Drop state
   const [draggingDocId, setDraggingDocId] = useState<string | null>(null);
@@ -960,22 +941,6 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     return map;
   }, [allRollupTodos]);
 
-  const rollupTodosByNote = useMemo(() => {
-    const map = new Map<
-      string,
-      { doc: Document; items: { doc: Document; blockId: string; content: string; checked: boolean }[] }
-    >();
-    for (const item of allRollupTodos) {
-      const existing = map.get(item.doc.id);
-      if (existing) {
-        existing.items.push(item);
-      } else {
-        map.set(item.doc.id, { doc: item.doc, items: [item] });
-      }
-    }
-    return map;
-  }, [allRollupTodos]);
-
   const totalOpenTodos = useMemo(() => {
     let count = 0;
     for (const d of docs) {