feat: highlight missing volumes in Prowlarr search results

API extracts volume numbers from release titles and matches them against
missing volumes sent by the frontend. Matched results are highlighted in
green with badges indicating which missing volumes were found.

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

apps/backoffice/lib/i18n/en.ts

@@ -514,6 +514,7 @@ const en: Record<TranslationKey, string> = {
   "prowlarr.sending": "Sending...",
   "prowlarr.sentSuccess": "Sent to qBittorrent",
   "prowlarr.sentError": "Failed to send to qBittorrent",
+  "prowlarr.missingVol": "Vol. {{vol}} missing",
 
   // Settings - qBittorrent
   "settings.qbittorrent": "qBittorrent",