fix(focus): list rows and menu items are not Tab stops

A ListRow or MenuItem Button wears no plate (Button::plate declines them),
so it has no role in the walk either: a list's rows are the list's to walk,
not Tab's — cce-files' browse page would otherwise be a hundred stops.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

 src/widget/input/button.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/widget/input/button.rs b/src/widget/input/button.rs
index ccee436..c765ee3 100644
--- a/src/widget/input/button.rs
+++ b/src/widget/input/button.rs
@@ -472,8 +472,13 @@ impl Paint for Button {
 }
 
 impl Input for Button {
+    /// A plate — except a ListRow or MenuItem, which wears no plate (see
+    /// [`Button::plate`]): a list's rows are walked by the list, not by Tab.
     fn focus_role(&self) -> crate::widget::FocusRole {
-        crate::widget::FocusRole::Plate
+        match self.kind {
+            ButtonKind::ListRow | ButtonKind::MenuItem => crate::widget::FocusRole::None,
+            _ => crate::widget::FocusRole::Plate,
+        }
     }
     fn on_event(&mut self, event: &Event, ectx: &mut EventCtx) -> bool {
         match event {