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/MonitoringForm.tsx

@@ -67,7 +67,7 @@ export function MonitoringForm({ libraryId, monitorEnabled, scanMode, watcherEna
             disabled={isPending}
             className="w-3.5 h-3.5 rounded border-border text-warning focus:ring-warning"
           />
-          <span title="Real-time file watcher">⚡</span>
+          <span title="Surveillance des fichiers en temps réel">⚡</span>
         </label>
         
         <select
@@ -76,10 +76,10 @@ export function MonitoringForm({ libraryId, monitorEnabled, scanMode, watcherEna
           disabled={isPending}
           className="px-3 py-1.5 text-sm rounded-lg border border-border bg-card text-foreground focus:ring-2 focus:ring-primary focus:border-primary disabled:opacity-50"
         >
-          <option value="manual">Manual</option>
-          <option value="hourly">Hourly</option>
-          <option value="daily">Daily</option>
-          <option value="weekly">Weekly</option>
+          <option value="manual">Manuel</option>
+          <option value="hourly">Toutes les heures</option>
+          <option value="daily">Quotidien</option>
+          <option value="weekly">Hebdomadaire</option>
         </select>
         
         <button