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/hardcover/query.ts

@@ -0,0 +1,28 @@
+import { FreshContext, Handlers } from "$fresh/server.ts";
+import { searchBook } from "@lib/hardcover.ts";
+import { AccessDeniedError, BadRequestError } from "@lib/errors.ts";
+
+const GET = async (
+  req: Request,
+  ctx: FreshContext,
+) => {
+  const session = ctx.state.session;
+  if (!session) {
+    throw new AccessDeniedError();
+  }
+
+  const u = new URL(req.url);
+  const query = u.searchParams.get("q");
+
+  if (!query) {
+    throw new BadRequestError();
+  }
+
+  const books = await searchBook(query);
+  console.log("Hardcover search results:", JSON.stringify(books).slice(0, 500));
+  return new Response(JSON.stringify(books));
+};
+
+export const handler: Handlers = {
+  GET,
+};