fix(TopBar): add selectedIndex boundary protection in keyboard nav

Guard against out-of-bounds access when search results change during
keyboard navigation. Check selectedIndex < totalItems before accessing
arrays.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

components/TopBar.tsx

@@ -126,11 +126,12 @@ export default function TopBar({ onOpenOptions }: { onOpenOptions: () => void })
       setSelectedIndex((prev) => (prev > 0 ? prev - 1 : prev));
     } else if (e.key === 'Enter') {
       e.preventDefault();
-      if (selectedIndex >= 0) {
+      if (selectedIndex >= 0 && selectedIndex < totalItems) {
         if (searchQuery.trim()) {
           handleSelectFeature(searchResults[selectedIndex]);
         } else {
           const selectedQuery = displayedHistory[selectedIndex];
+          if (selectedQuery) {
             setSearchQuery(selectedQuery);
             setSelectedIndex(-1);
             const matched = FEATURES.find(
@@ -138,6 +139,7 @@ export default function TopBar({ onOpenOptions }: { onOpenOptions: () => void })
             );
             if (matched) handleSelectFeature(matched);
           }
+        }
       } else if (searchQuery.trim() && searchResults.length > 0) {
         handleSelectFeature(searchResults[0]);
       }