feat: books fetch on SSR in book reader

src/app/books/[bookId]/page.tsx

@@ -1,13 +1,36 @@
 import { Suspense } from "react";
 import { ClientBookPage } from "@/components/reader/ClientBookPage";
 import { BookSkeleton } from "@/components/skeletons/BookSkeleton";
+import { BookService } from "@/lib/services/book.service";
+import { ERROR_CODES } from "@/constants/errorCodes";
+import { AppError } from "@/utils/errors";
+import { redirect } from "next/navigation";
 
 export default async function BookPage({ params }: { params: Promise<{ bookId: string }> }) {
   const { bookId } = await params;
 
-  return (
-    <Suspense fallback={<BookSkeleton />}>
-      <ClientBookPage bookId={bookId} />
-    </Suspense>
-  );
+  try {
+    // SSR: Fetch directly on server instead of client-side XHR
+    const data = await BookService.getBook(bookId);
+    const nextBook = await BookService.getNextBook(bookId, data.book.seriesId);
+
+    return (
+      <Suspense fallback={<BookSkeleton />}>
+        <ClientBookPage bookId={bookId} initialData={{ ...data, nextBook }} />
+      </Suspense>
+    );
+  } catch (error) {
+    // If config is missing, redirect to settings
+    if (error instanceof AppError && error.code === ERROR_CODES.KOMGA.MISSING_CONFIG) {
+      redirect("/settings");
+    }
+
+    // Pass error to client component
+    const errorCode = error instanceof AppError ? error.code : ERROR_CODES.BOOK.NOT_FOUND;
+    return (
+      <Suspense fallback={<BookSkeleton />}>
+        <ClientBookPage bookId={bookId} initialError={errorCode} />
+      </Suspense>
+    );
+  }
 }