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>

README.md

@@ -12,6 +12,8 @@ A terminal UI to search for movies and series with [Radarr](https://radarr.video
   lists from [Trakt](https://trakt.tv): trending now, most watched this week, anticipated, popular,
   and the US box office for movies. `[` and `]` switch lists; titles already in your library are
   ticked, the others can be added right there (Enter). Needs a free Trakt client ID (see Configure).
+- **Library**: movies and series with their status; the dot before a title turns blue while it
+  is downloading, and the details say how far.
 - **Season posters**: in a series' seasons and episodes, the poster follows the selected season.
 - **Cast**: with a Trakt client ID, the details pane also lists the director (or the creators of a
   series) and the cast with their roles, below the plot, in every view.