Library: mark titles that are downloading

While the Library is visible it reads the Radarr and Sonarr queues (on
opening, every 10 s, and shortly after a grab) and matches them to the
titles by movieId / seriesId. Those titles get a blue dot instead of the
green or grey one, and their details say how far the download is.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/arr/queue.go

@@ -31,6 +31,8 @@ type QueueItem struct {
 	DownloadID            string          `json:"downloadId"` // the download client's id, e.g. SABnzbd's nzo_id
 	Indexer               string          `json:"indexer"`
 	Protocol              string          `json:"protocol"`
+	MovieID               int             `json:"movieId,omitempty"`  // Radarr
+	SeriesID              int             `json:"seriesId,omitempty"` // Sonarr
 
 	// Present depending on the include* parameters of the request.
 	Movie   *QueueMovie   `json:"movie,omitempty"`