R5.7: Gitea #1, ElyShow's slide strip scrolls with the wheel; R1 PASS

The strip's list sat in a ContextMenu host with no size, so it grew
with its content and never overflowed. The host now fills its column,
as ElyPDF's do; a 24-slide test wheels to the last slide.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

apps/ely-show/src/slides.rs

@@ -234,6 +234,7 @@ impl Render for Strip {
                 let label = format!("{} {}", part + 1, slide.name);
                 div()
                     .id(("show-slide", part))
+                    .debug_selector(move || format!("show-slide-{part}"))
                     .tab_index(0)
                     .focus_ring(cx)
                     .flex()
@@ -301,6 +302,7 @@ impl Render for Strip {
             .children(slides);
         div()
             .size_full()
-            .child(ContextMenu::new("show-strip-menu", popup(cx)).child(list))
+            // A sized host lets the list overflow and scroll.
+            .child(ContextMenu::new("show-strip-menu", popup(cx)).size_full().child(list))
     }
 }