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).

web/src/series.ts

@@ -11,7 +11,7 @@ interface SeriesItem {
 }
 
 function renderSeriesCard(series: SeriesItem, libraryId: string): string {
-  const href = `/bookshelf?series_filter=${encodeURIComponent(series.name)}&sort=series&library_id=${libraryId}`;
+  const href = `/series/detail?name=${encodeURIComponent(series.name)}&library_id=${libraryId}`;
   const coverCount = series.cover_paths.length;
   const coverClass = `cover-count-${coverCount}`;
 
@@ -152,3 +152,22 @@ Alpine.data("seriesPage", () => ({
     }
   },
 }));
+
+Alpine.data("seriesDetailPage", () => ({
+  initSeriesDetailPage() {
+    const librarySelect = document.getElementById(
+      "library-select",
+    ) as HTMLSelectElement;
+    if (librarySelect) {
+      librarySelect.addEventListener("change", () => {
+        if (librarySelect.value) {
+          const url = new URL(window.location.href);
+          const currentLib = url.searchParams.get("library_id");
+          if (currentLib === librarySelect.value) return;
+          url.searchParams.set("library_id", librarySelect.value);
+          window.location.href = url.toString();
+        }
+      });
+    }
+  },
+}));