perf: optimize scrolling and image loading performance

Added performance optimizations to all library browser views:

- Added cacheExtent: 500 to all GridView/ListView builders to pre-render
  items and reduce stuttering during scrolling
- Wrapped grid items in RepaintBoundary to isolate repaints and improve
  performance
- Optimized CachedNetworkImage with:
  - fadeInDuration/fadeOutDuration: Duration.zero to remove animation overhead
  - memCacheHeight: 300 to limit in-memory cache size
  - maxHeightDiskCache: 600 to resize images for better performance

These changes should significantly reduce the stuttering observed when
scrolling the authors grid and filtering books, especially on first load.

lib/features/library_browser/view/filtered_library_items_page.dart

@@ -84,6 +84,7 @@ class FilteredLibraryItemsPage extends HookConsumerWidget {
 
               return GridView.builder(
                 padding: const EdgeInsets.all(16),
+                cacheExtent: 500,  // Pre-render items for smoother scrolling
                 gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
                   crossAxisCount: 3,
                   childAspectRatio: 0.65,
@@ -93,7 +94,9 @@ class FilteredLibraryItemsPage extends HookConsumerWidget {
                 itemCount: response.results.length,
                 itemBuilder: (context, index) {
                   final item = response.results[index];
-                  return LibraryItemCard(item: item);
+                  return RepaintBoundary(
+                    child: LibraryItemCard(item: item),
+                  );
                 },
               );
             },
@@ -247,6 +250,10 @@ class LibraryItemCard extends ConsumerWidget {
                   ? CachedNetworkImage(
                       imageUrl: imageUrl,
                       fit: BoxFit.cover,
+                      fadeInDuration: Duration.zero,  // Remove fade animation for better performance
+                      fadeOutDuration: Duration.zero,
+                      memCacheHeight: 300,  // Limit memory cache size
+                      maxHeightDiskCache: 600,  // Limit disk cache size
                       httpHeaders: {
                         if (apiSettings.activeUser?.authToken != null)
                           'Authorization':

lib/features/library_browser/view/library_authors_page.dart

@@ -37,6 +37,7 @@ class LibraryAuthorsPage extends HookConsumerWidget {
 
           return GridView.builder(
             padding: const EdgeInsets.all(16),
+            cacheExtent: 500,  // Pre-render items for smoother scrolling
             gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
               crossAxisCount: 2,
               childAspectRatio: 0.75,
@@ -46,7 +47,9 @@ class LibraryAuthorsPage extends HookConsumerWidget {
             itemCount: sortedAuthors.length,
             itemBuilder: (context, index) {
               final author = sortedAuthors[index];
-              return AuthorCard(author: author);
+              return RepaintBoundary(
+                child: AuthorCard(author: author),
+              );
             },
           );
         },
@@ -125,6 +128,10 @@ class AuthorCard extends HookConsumerWidget {
                         'Authorization': 'Bearer ${apiSettings.activeUser?.authToken}',
                       },
                       fit: BoxFit.cover,
+                      fadeInDuration: Duration.zero,  // Remove fade animation for better performance
+                      fadeOutDuration: Duration.zero,
+                      memCacheHeight: 300,  // Limit memory cache size
+                      maxHeightDiskCache: 600,  // Limit disk cache size
                       placeholder: (context, url) => Container(
                         color: Theme.of(context).colorScheme.surfaceContainerHighest,
                         child: const Center(

lib/features/library_browser/view/library_genres_page.dart

@@ -29,6 +29,7 @@ class LibraryGenresPage extends HookConsumerWidget {
 
           return ListView.builder(
             padding: const EdgeInsets.symmetric(vertical: 8),
+            cacheExtent: 500,  // Pre-render items for smoother scrolling
             itemCount: sortedGenres.length,
             itemBuilder: (context, index) {
               final genre = sortedGenres[index];

lib/features/library_browser/view/library_series_page.dart

@@ -38,6 +38,7 @@ class LibrarySeriesPage extends HookConsumerWidget {
 
           return ListView.builder(
             padding: const EdgeInsets.symmetric(vertical: 8),
+            cacheExtent: 500,  // Pre-render items for smoother scrolling
             itemCount: seriesList.length,
             itemBuilder: (context, index) {
               final series = seriesList[index];