feat: the gallery navigates in plate terms

Opt into cce-ui's Tab traversal (`Application::plate_navigation`): Tab and
Shift+Tab walk the exhibits' plates and wells in reading order, each lighting
its own rim.

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

 src/main.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/main.rs b/src/main.rs
index a99c1b5..a2914bd 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1209,6 +1209,11 @@ impl cce_ui::engine::Application for State {
         state
     }
 
+    /// The gallery navigates in plate terms: Tab walks the exhibits.
+    fn plate_navigation(&self) -> bool {
+        true
+    }
+
     fn settings(&self) -> cce_ui::engine::WindowSettings {
         let title = match self.child_kind {
             Some(kind) => kind.title().to_string(),