New sidebar and folder view (#263)

src-web/hooks/useActiveFolderId.ts

@@ -0,0 +1,11 @@
+import { useSearch } from '@tanstack/react-router';
+import { atom } from 'jotai';
+import { useEffect } from 'react';
+import { jotaiStore } from '../lib/jotai';
+
+export const activeFolderIdAtom = atom<string | null>(null);
+
+export function useSubscribeActiveFolderId() {
+  const { folder_id } = useSearch({ strict: false });
+  useEffect(() => jotaiStore.set(activeFolderIdAtom, folder_id ?? null), [folder_id]);
+}