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/report.rs

@@ -73,7 +73,7 @@ pub struct BuildTarget<'a> {
 /// the build thread; long-lived views are expected to be `Send + Sync`
 /// because builds may run inside async tasks. The pull flow only emits the
 /// [`BuildView::message`], [`BuildView::progress`] and
-/// [`BuildView::progress`] events — no target, phases or outcome.
+/// [`BuildView::byte_progress`] events — no target, phases or outcome.
 pub trait BuildView: Send + Sync {
     /// The build target was identified; the events that follow belong to it
     /// (including the earliest subprocess output, e.g. a chroot download).