feat: add batch metadata jobs, series filters, and translate backoffice to French

- Add metadata_batch job type with background processing via tokio::spawn
- Auto-apply metadata only when single result at 100% confidence
- Support primary + fallback provider per library, "none" to opt out
- Add batch report/results API endpoints and job detail UI
- Add series_status and has_missing filters to both series listing pages
- Add GET /series/statuses endpoint for dynamic filter options
- Normalize series_metadata status values (migration 0036)
- Hide ComicVine provider tab when no API key configured
- Translate entire backoffice UI from English to French

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/backoffice/app/libraries/[id]/books/page.tsx

@@ -38,14 +38,14 @@ export default async function LibraryBooksPage({
     coverUrl: getBookCoverUrl(book.id)
   }));
 
-  const seriesDisplayName = series === "unclassified" ? "Unclassified" : series;
+  const seriesDisplayName = series === "unclassified" ? "Non classé" : series;
   const totalPages = Math.ceil(booksPage.total / limit);
 
   return (
     <div className="space-y-6">
       <LibrarySubPageHeader
         library={library}
-        title={series ? `Books in "${seriesDisplayName}"` : "All Books"}
+        title={series ? `Livres de "${seriesDisplayName}"` : "Tous les livres"}
         icon={
           <svg className="w-8 h-8" fill="none" stroke="currentColor" viewBox="0 0 24 24">
             <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 6.253v13m0-13C10.832 5.477 9.246 5 7.5 5S4.168 5.477 3 6.253v13C4.168 18.477 5.754 18 7.5 18s3.332.477 4.5 1.253m0-13C13.168 5.477 14.754 5 16.5 5c1.747 0 3.332.477 4.5 1.253v13C19.832 18.477 18.247 18 16.5 18c-1.746 0-3.332.477-4.5 1.253" />
@@ -53,9 +53,9 @@ export default async function LibraryBooksPage({
         }
         iconColor="text-success"
         filterInfo={series ? {
-          label: `Showing books from series "${seriesDisplayName}"`,
+          label: `Livres de la série "${seriesDisplayName}"`,
           clearHref: `/libraries/${id}/books`,
-          clearLabel: "View all books"
+          clearLabel: "Voir tous les livres"
         } : undefined}
       />
 
@@ -71,7 +71,7 @@ export default async function LibraryBooksPage({
           />
         </>
       ) : (
-        <EmptyState message={series ? `No books in series "${seriesDisplayName}"` : "No books in this library yet"} />
+        <EmptyState message={series ? `Aucun livre dans la série "${seriesDisplayName}"` : "Aucun livre dans cette bibliothèque"} />
       )}
     </div>
   );