pull,ui,report: render the pull downloads as byte progress

The pull downloads reported through the plain count port only because
byte_progress landed on main after the branch was cut. PullView now
implements it with a byte-counter template in the transfer-style
family (same shape, {bytes}/{total_bytes} counters, human-formatted by
indicatif), downloads emit through it, and the trait doc lists the
event among the ones the pull flow emits — un-duplicating the merged
'message, progress and progress' sentence.

src/pull.rs

@@ -503,8 +503,7 @@ async fn download_file_checksum_once(
         buffer.extend_from_slice(&chunk);
 
         if let Some(total) = total_size {
-            let index = min(buffer.len(), total as usize);
-            view.progress("Downloading...", index, total as usize);
+            view.byte_progress("Downloading...", min(buffer.len() as u64, total), total);
         }
     }