feat(readarr): add the downloads UI

Render the Readarr downloads table with the cancel download prompt and
the update downloads prompt, and dispatch it from ReadarrUi so the tab
is reachable.

The snapshot suite covers every block in DOWNLOADS_BLOCKS plus loading
and empty states. A second set of snapshots seeds a two row fixture and
selects the second row. Its rows deliberately have different completion
ratios, so that inverting the percentage calculation is caught rather
than cancelling out against a half finished download.

src/ui/readarr_ui/mod.rs

@@ -22,6 +22,7 @@ use super::{
   widgets::loading_block::LoadingBlock,
 };
 use crate::ui::readarr_ui::blocklist::BlocklistUi;
+use crate::ui::readarr_ui::downloads::DownloadsUi;
 use crate::ui::utils::{extract_monitored_disk_space_vec, extract_monitored_root_folders};
 use crate::{
   app::App,
@@ -36,6 +37,7 @@ use crate::{
 };
 
 mod blocklist;
+mod downloads;
 mod library;
 mod readarr_ui_utils;
 
@@ -56,6 +58,7 @@ impl DrawUi for ReadarrUi {
 
     match route {
       _ if LibraryUi::accepts(route) => LibraryUi::draw(f, app, content_area),
+      _ if DownloadsUi::accepts(route) => DownloadsUi::draw(f, app, content_area),
       _ if BlocklistUi::accepts(route) => BlocklistUi::draw(f, app, content_area),
       _ => (),
     }