Corregge chiusura diretta YouTube e stop sessione senza broadcast.

transition_live_broadcast richiede status, id e part; evita 500 in chiusura
diretta Match Live TV quando non c'è broadcast YouTube.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/youtube/broadcast_service.rb

@@ -50,10 +50,11 @@ module Youtube
     end
 
     def complete_broadcast!(broadcast_id)
+      return if broadcast_id.blank?
       return if @credential.blank? || missing_oauth_config?
 
       client = authorized_client
-      client.transition_live_broadcast(broadcast_id, "complete")
+      client.transition_live_broadcast("complete", broadcast_id, "id,status")
     rescue Google::Apis::Error
       nil
     end