fix(dl): take stalled from Transmission

A zero download rate is not a stalled torrent: one between peers reads
zero for a poll or two and finishes fine, and at §9.8's 15s cadence that
flicker would raise the one chip reserved for a download that never
finishes. Transmission already decides this with its own stalled window;
carry isStalled and use it.

crates/arr-api/src/downloads.rs

@@ -116,7 +116,10 @@ fn phase(torrent: &Torrent) -> DownloadPhase {
     } else {
         match torrent.state {
             TorrentState::Seeding => DownloadPhase::Seeding,
-            TorrentState::Downloading if torrent.download_rate == 0 => DownloadPhase::Stalled,
+            // Transmission's own verdict, not a zero rate: a torrent between
+            // peers reads zero for a poll or two and finishes fine, and
+            // §9.8's stalled chip is for the case that never does.
+            TorrentState::Downloading if torrent.is_stalled => DownloadPhase::Stalled,
             TorrentState::Downloading => DownloadPhase::Downloading,
             _ => DownloadPhase::Queued,
         }
@@ -148,6 +151,7 @@ mod tests {
                 download_rate: rate,
                 eta: None,
                 error: error.map(str::to_owned),
+                is_stalled: rate == 0,
                 download_dir: PathBuf::from("/downloads"),
                 labels: Vec::new(),
                 is_finished: false,