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/books/[id]/page.tsx

@@ -53,7 +53,7 @@ export default async function BookDetailPage({
       {/* Breadcrumb */}
       <div className="flex items-center gap-2 text-sm">
         <Link href="/libraries" className="text-muted-foreground hover:text-primary transition-colors">
-          Libraries
+          Bibliothèques
         </Link>
         <span className="text-muted-foreground">/</span>
         {library && (
@@ -88,7 +88,7 @@ export default async function BookDetailPage({
           <div className="w-48 aspect-[2/3] relative rounded-xl overflow-hidden shadow-card border border-border">
             <Image
               src={getBookCoverUrl(book.id)}
-              alt={`Cover of ${book.title}`}
+              alt={`Couverture de ${book.title}`}
               fill
               className="object-cover"
               unoptimized