fix: downgrade Trakt 403 log from ERR to WARN

Trakt returns 403 (not 404) for tmdb IDs it doesn't have in its
database. This is expected behavior, not an application error, so
logging at WARN avoids false alarm noise in production logs.

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

radarr/queue.go

@@ -78,7 +78,7 @@ func (c *Client) queueProcessor(tail state.ShutdownTail) {
 					continue
 				}
 
-				c.log.Error().
+				c.log.Warn().
 					Err(err).
 					Str("feed_title", feedItem.Title).
 					Str(fmt.Sprintf("feed_%s_id", mdp), mdi).