fix(mgr): restore hovered fallback for %s/%d shell-formatting when nothing is selected

The Splatable impl for Mgr used to fall back to the hovered item via
Tab::selected_or_hovered_urls() when the selection was empty, the same
convention used elsewhere (yank, copy, remove, open). PR #4108 rewrote
this into MgrSnap/TabSnap but only ported the plain selected list,
dropping the hovered fallback. This made %s and %d expand to nothing
when hovering a file without an explicit selection.

Restore the fallback in MgrSnap::selected(), which both %s/%S and
%d/%D read from.

Resolves #4132

yazi-core/src/mgr/snap.rs

@@ -1,3 +1,5 @@
+use std::iter;
+
 use yazi_fs::Splatable;
 use yazi_shared::url::{AsUrl, Url, UrlBuf};
 
@@ -24,14 +26,17 @@ impl Splatable for MgrSnap {
 
 	fn selected(&self, tab: usize, mut idx: Option<usize>) -> impl Iterator<Item = Url<'_>> {
 		idx = idx.and_then(|i| i.checked_sub(1));
-		tab
-			.checked_sub(1)
-			.and_then(|tab| self.tabs.get(tab))
-			.map_or_else(|| &[][..], |s| &s.selected)
-			.iter()
-			.skip(idx.unwrap_or(0))
-			.take(if idx.is_some() { 1 } else { usize::MAX })
-			.map(AsUrl::as_url)
+
+		// Fall back to the hovered item when nothing is explicitly selected, the
+		// same convention `Tab::selected_or_hovered_urls()` used before #4108.
+		let urls: Box<dyn Iterator<Item = &UrlBuf>> =
+			match tab.checked_sub(1).and_then(|tab| self.tabs.get(tab)) {
+				Some(s) if !s.selected.is_empty() => Box::new(s.selected.iter()),
+				Some(s) => Box::new(s.hovered.iter()),
+				None => Box::new(iter::empty()),
+			};
+
+		urls.skip(idx.unwrap_or(0)).take(if idx.is_some() { 1 } else { usize::MAX }).map(AsUrl::as_url)
 	}
 
 	fn hovered(&self, tab: usize) -> Option<Url<'_>> {
@@ -52,3 +57,44 @@ impl Splatable for MgrSnap {
 			.map(AsUrl::as_url)
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use std::path::Path;
+
+	use super::*;
+
+	fn url(s: &str) -> UrlBuf { UrlBuf::from(Path::new(s)) }
+
+	fn snap(selected: &[&str], hovered: Option<&str>) -> MgrSnap {
+		MgrSnap {
+			tab:    0,
+			tabs:   vec![TabSnap {
+				hovered:  hovered.map(url),
+				selected: selected.iter().map(|s| url(s)).collect(),
+			}],
+			yanked: vec![],
+		}
+	}
+
+	#[test]
+	fn selected_falls_back_to_hovered_when_empty() {
+		let s = snap(&[], Some("hovered"));
+
+		assert_eq!(s.selected(1, None).collect::<Vec<_>>(), [url("hovered").as_url()]);
+	}
+
+	#[test]
+	fn selected_prefers_explicit_selection_over_hovered() {
+		let s = snap(&["a", "b"], Some("hovered"));
+
+		assert_eq!(s.selected(1, None).collect::<Vec<_>>(), [url("a").as_url(), url("b").as_url()]);
+	}
+
+	#[test]
+	fn selected_empty_when_nothing_selected_or_hovered() {
+		let s = snap(&[], None);
+
+		assert_eq!(s.selected(1, None).count(), 0);
+	}
+}