refactor: Consolidate workspace utilities into new workspaceUtils.ts with typed entry keys, replacing appLayoutUtils.ts, and update related components.

frontend/src/sidebar/useSidebarProps.ts

@@ -1,6 +1,6 @@
 import { useMemo } from 'react';
 import type { DragEvent } from 'react';
-import { TAG_FILTER_UNTAGGED } from '../app/appLayoutUtils';
+import { TAG_FILTER_UNTAGGED } from '../app/workspaceUtils';
 import type { StatusMessage } from '../hooks/documents/store/useDocumentsStore';
 
 type Identifier = string | number;