fix: improve navigation stack and ensure square cover aspect ratios

Navigation fixes:
- Change goNamed to pushNamed in all library browser pages
- Maintains proper back navigation stack
- Back button now goes step by step instead of to beginning
- Prevents app from closing when navigating back from book detail

Grid layout fixes:
- Book covers are now always square (1.0 aspect ratio)
- Overall card aspect ratio is 0.75 to provide space for text
- Wrap cover in AspectRatio widget instead of using Expanded
- Ensures title and author info always visible below covers
- Fixes issue where book info was missing in series view

lib/features/library_browser/view/filtered_library_items_page.dart

@@ -77,7 +77,7 @@ class FilteredLibraryItemsPage extends HookConsumerWidget {
                 padding: const EdgeInsets.all(16),
                 gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
                   crossAxisCount: 3,
-                  childAspectRatio: 0.65,
+                  childAspectRatio: 0.75,
                   crossAxisSpacing: 12,
                   mainAxisSpacing: 16,
                 ),
@@ -192,7 +192,7 @@ class LibraryItemCard extends ConsumerWidget {
     return InkWell(
       onTap: () {
         // Navigate to item detail page
-        context.goNamed(
+        context.pushNamed(
           Routes.libraryItem.name,
           pathParameters: {'itemId': item.id},
         );
@@ -200,8 +200,9 @@ class LibraryItemCard extends ConsumerWidget {
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.stretch,
         children: [
-          // Book cover
-          Expanded(
+          // Book cover - always square
+          AspectRatio(
+            aspectRatio: 1.0,
             child: ClipRRect(
               borderRadius: BorderRadius.circular(8),
               child: imageUrl != null

lib/features/library_browser/view/library_authors_page.dart

@@ -105,7 +105,7 @@ class AuthorCard extends HookConsumerWidget {
       child: InkWell(
         onTap: () {
           // Navigate to filtered items page with author filter
-          context.goNamed(
+          context.pushNamed(
             Routes.libraryFiltered.name,
             extra: {
               'filter': AuthorFilter(author.id),

lib/features/library_browser/view/library_genres_page.dart

@@ -86,7 +86,7 @@ class GenreListTile extends StatelessWidget {
         trailing: const Icon(Icons.chevron_right),
         onTap: () {
           // Navigate to filtered items page with genre filter
-          context.goNamed(
+          context.pushNamed(
             Routes.libraryFiltered.name,
             extra: {
               'filter': GenreFilter(genre),

lib/features/library_browser/view/library_series_page.dart

@@ -110,7 +110,7 @@ class SeriesListTile extends StatelessWidget {
         trailing: const Icon(Icons.chevron_right),
         onTap: () {
           // Navigate to filtered items page with series filter
-          context.goNamed(
+          context.pushNamed(
             Routes.libraryFiltered.name,
             extra: {
               'filter': SeriesFilter(series.id),