style(simulation): cargo fmt

Formatting normalization caught by pre-push hook.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/simulation/save_io.rs

@@ -989,10 +989,7 @@ mod tests {
         // Clear the resource to prove load restores it, not the pre-existing value.
         world.insert_resource(SelectedBookmark::default());
         assert!(
-            world
-                .resource::<SelectedBookmark>()
-                .bookmark_id
-                .is_none(),
+            world.resource::<SelectedBookmark>().bookmark_id.is_none(),
             "bookmark must be cleared before load"
         );