feat: integrate Hardcover API for books

- Add lib/hardcover.ts with GraphQL client for Hardcover API
- Add routes/api/books/[name].ts for creating books via Hardcover ID
- Add routes/api/books/enhance/[name].ts for enhancing books
- Add routes/api/hardcover/query.ts for searching books
- Add routes/books/[name].tsx and index.tsx for book pages

routes/api/books/index.ts

@@ -0,0 +1,10 @@
+import { Handlers } from "$fresh/server.ts";
+import { json } from "@lib/helpers.ts";
+import { fetchResource } from "@lib/marka/index.ts";
+
+export const handler: Handlers = {
+  async GET() {
+    const books = await fetchResource("books");
+    return json(books?.content);
+  },
+};