feat(series): add dedicated series detail page instead of bookshelf filter

Create a new /series/detail?name=X&library_id=Y SSR page that shows
all books in a specific series, replacing the broken approach of
linking to /bookshelf?series_filter=X (the bookshelf SSR handler
ignores all filter query params).

The series detail page features:
- Back link to /series browse page
- Library selector dropdown (full page navigation on change)
- Series name header with book count badge
- Book grid using the shared BookCard template
- Empty state for series with no books

Update all links to point to the new page:
- Series cards on /series browse page
- Series badge on book detail page
- JS-rendered cards in series.ts switchLibrary

Add seriesDetailPage Alpine component for the detail page's
library switcher (simple navigation, no AJAX needed).

templates/series.templ

@@ -95,7 +95,7 @@ templ Series(user User, seriesList []SeriesCardData, libData []LibraryData, curr
 }
 
 templ SeriesCard(series SeriesCardData, libraryID string) {
-	<a href={ "/bookshelf?series_filter=" + url.QueryEscape(series.Name) + "&sort=series&library_id=" + libraryID } class="block">
+	<a href={ "/series/detail?name=" + url.QueryEscape(series.Name) + "&library_id=" + libraryID } class="block">
 		<div class="series-card rounded-lg overflow-hidden cursor-pointer hover:shadow-lg transition-shadow" style="background-color: var(--bg-secondary);">
 			<div class={ "stacked-covers cover-count-" + fmt.Sprintf("%d", len(series.CoverPaths)) }>
 				for i, cover := range series.CoverPaths {