prune,ui: show the removal pass, prefix the sizing spinner

Confirming a 500 GiB prune went silent under "Removing:" for minutes:
drive an indicatif bar from the plan's sizes through a new
apply_with_progress observer, in the deb live view's layout — the
running count behind the spinner on the first line, the byte bar with
its counters on the second. The removed path is not rendered: it
fights the bar on a narrow terminal, and the failed-removal errors
name the paths that matter. --force plans no sizes and gets the count
line only.

The dry-run size spinner lacked the "> " prompt prefix the other
one-line waits carry; wait_spinner renders it too now.

src/ui.rs

@@ -7,6 +7,7 @@ pub mod deb;
 /// yes/no confirmation
 pub mod prompt;
 
+use crossterm::terminal;
 #[cfg(test)]
 use indicatif::ProgressDrawTarget;
 use indicatif::{MultiProgress, ProgressBar, ProgressStyle};
@@ -41,16 +42,59 @@ pub(crate) fn transfer_style() -> ProgressStyle {
 }
 
 /// A standalone spinner for one-line waits outside a build view (the
-/// prune size pass): braille frames over the message, drawn only on
-/// terminals. Callers finish it with [`ProgressBar::finish_and_clear`].
+/// prune size pass): braille frames over the message behind the `> `
+/// prompt prefix, drawn only on terminals. Callers finish it with
+/// [`ProgressBar::finish_and_clear`].
 pub fn wait_spinner(msg: &str) -> ProgressBar {
     let pb = ProgressBar::new_spinner();
-    pb.set_style(ProgressStyle::with_template("{spinner:.blue} {msg}").expect("spinner template"));
+    pb.set_style(
+        ProgressStyle::with_template("> {spinner:.blue} {msg}").expect("spinner template"),
+    );
     pb.set_message(msg.to_string());
     pb.enable_steady_tick(Duration::from_millis(120));
     pb
 }
 
+/// Width of the terminal in columns, or `None` when it cannot be determined
+pub(crate) fn terminal_width() -> Option<usize> {
+    terminal::size().ok().map(|(cols, _)| cols as usize)
+}
+
+/// Removal progress bar of `pkh prune`, in the deb live view's layout:
+/// the running count behind the spinner on the first line, the byte bar
+/// with its counters on the second when the plan carries sizes (`--force`
+/// skips the sizing and gets the count line only). The removed path is
+/// deliberately not rendered — it fights the bar on a narrow terminal,
+/// and the failed-removal errors name the paths that matter. Drive it
+/// with [`removal_progress`]; finish it with
+/// [`ProgressBar::finish_and_clear`].
+pub fn removal_bar(multi: &MultiProgress, total_bytes: u64) -> ProgressBar {
+    let pb = multi.add(ProgressBar::new(total_bytes));
+    let template = if total_bytes > 0 {
+        "> {spinner:.blue} {prefix}\n [{bar:24.cyan/blue}] {bytes}/{total_bytes}"
+    } else {
+        "> {spinner:.blue} {prefix}"
+    };
+    pb.set_style(
+        ProgressStyle::with_template(template)
+            .expect("removal template")
+            .progress_chars("=> "),
+    );
+    pb.enable_steady_tick(Duration::from_millis(120));
+    pb
+}
+
+/// Advance the removal bar to the `idx`-th of `count` artifact;
+/// `done` bytes already freed
+pub fn removal_progress(bar: &ProgressBar, idx: usize, count: usize, done: u64) {
+    bar.set_prefix(format!("Removing {}/{}", idx + 1, count));
+    if let Some(total) = bar.length()
+        && total > 0
+    {
+        bar.set_position(done.min(total));
+    }
+}
+
 /// Create a spinner-style progress bar attached to `multi`, returning the bar
 /// and a callback compatible with [`crate::ProgressCallback`]
 pub fn create_progress_bar(