fix: remove unnecessary image sizing utilities from book pages

- Removed `object-cover` from card view to prevent forced cropping
- Removed `aspect-[3/4]` from detail view for flexible image display
- Improved visual consistency between card and detail layouts

Author: eottabom

components/BookCard.tsx

@@ -11,7 +11,7 @@ export default function BookCard({ meta }: { meta: BookMeta }) {
                         <img
                             src={meta.cover}
                             alt={meta.title}
-                            className="w-32 h-44 sm:w-36 sm:h-52 lg:w-40 lg:h-56 object-cover rounded-lg"
+                            className="w-32 h-44 sm:w-36 sm:h-52 lg:w-40 lg:h-56 rounded-lg"
                             loading="lazy"
                         />
                     )}

pages/book/[slug].tsx

@@ -87,7 +87,7 @@ export default function BookDetail({mdxSource, title, author, date, updated, sum
                             alt={title}
                             className="mx-auto mb-6
                                       w-48 sm:w-56 lg:w-64
-                                      aspect-[3/4] object-cover
+                                      object-cover
                                       rounded-xl shadow-sm"
                             loading="lazy"
                             width={384} height={512} // CLS 방지용 대략치