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/components/LibraryForm.tsx

@@ -17,7 +17,7 @@ export function LibraryForm({ initialFolders, action }: LibraryFormProps) {
     <form action={action}>
       <FormRow>
         <FormField className="flex-1 min-w-48">
-          <FormInput name="name" placeholder="Library name" required />
+          <FormInput name="name" placeholder="Nom de la bibliothèque" required />
         </FormField>
         <FormField className="flex-1 min-w-64">
           <input type="hidden" name="root_path" value={selectedPath} />
@@ -30,7 +30,7 @@ export function LibraryForm({ initialFolders, action }: LibraryFormProps) {
       </FormRow>
       <div className="mt-4 flex justify-end">
         <Button type="submit" disabled={!selectedPath}>
-          Add Library
+          Ajouter une bibliothèque
         </Button>
       </div>
     </form>