Refactor shelves UI and jobs

src/lib/hooks/useShelves.ts

@@ -0,0 +1,40 @@
+/**
+ * Component: Shelves Hook
+ * Documentation: documentation/frontend/components.md
+ */
+
+'use client';
+
+import useSWR from 'swr';
+import { useAuth } from '@/contexts/AuthContext';
+import { fetchWithAuth } from '@/lib/utils/api';
+import { ShelfBook } from './useGoodreadsShelves';
+
+export interface GenericShelf {
+  id: string;
+  type: 'goodreads' | 'hardcover';
+  name: string;
+  sourceId: string; // Either rssUrl or listId
+  lastSyncAt: string | null;
+  createdAt: string;
+  bookCount: number | null;
+  books: ShelfBook[];
+}
+
+const fetcher = (url: string) => fetchWithAuth(url).then((res) => res.json());
+
+export function useShelves() {
+  const { accessToken } = useAuth();
+
+  const endpoint = accessToken ? '/api/user/shelves' : null;
+
+  const { data, error, isLoading } = useSWR(endpoint, fetcher, {
+    refreshInterval: 30000,
+  });
+
+  return {
+    shelves: (data?.shelves || []) as GenericShelf[],
+    isLoading,
+    error,
+  };
+}