✨(summary) add localization support for transcription context text

Transcription and summarization results were always generated
using a French text structure (e.g. "Réunion du..."), regardless
of user preference or meeting language. Introduced basic localization
support to adapt generated string languages.

src/backend/core/recording/event/notification.py

@@ -167,6 +167,7 @@ class NotificationService:
                 owner_access.user.timezone
             ).strftime("%H:%M"),
             "download_link": f"{get_recording_download_base_url()}/{recording.id}",
+            "context_language": owner_access.user.language,
         }
 
         headers = {