Queue up to 1024 commands, so Download latest 100 does not hang (#154)

The worker's queue held 64 commands, and a web request that queues work waits inside itself for a
free place. Download latest lets you ask for up to 100 and sends one command a file, so past 64
the request waited for the worker to finish whole downloads, one after another, an hour for 100;
Cloudflare gave up on it after 100 s and the page said it failed, though most were queued. Until
it finished, adding a feed, Refresh, Download and socket commands all waited for a place too. A
command is a few bytes; the queue now has room for any one request's.

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

src/main.rs

@@ -594,7 +594,10 @@ async fn daemon(
         Err(e) => tracing::warn!(error = %format!("{e:#}"), "could not retire feeds whose OPML is no longer in config"),
     }
 
-    let (tx_cmd, mut rx_cmd) = mpsc::channel::<Cmd>(64);
+    // Room for any one request's commands: a web request waits inside itself for a free place,
+    // and Download latest sends up to 100. With 64 the rest waited on downloads an hour long, and
+    // every other request that queues work waited behind them (#154).
+    let (tx_cmd, mut rx_cmd) = mpsc::channel::<Cmd>(1024);
 
     let web = start_web(&ctx, &config_path, web_addr, &tx_cmd, &events).await?;
     // status and reload are answered by the socket itself; everything else waits its turn in the