Fix UI not displaying search results

Backend returns { data: [...] } but UI was reading .results instead of .data.

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

ui/src/pages/executions/ExecutionExplorer.tsx

@@ -12,7 +12,7 @@ export function ExecutionExplorer() {
   const { data, isLoading, isFetching } = useSearchExecutions(searchRequest);
 
   const total = data?.total ?? 0;
-  const results = data?.results ?? [];
+  const results = data?.data ?? [];
 
   // Derive stats from current search results
   const failedCount = results.filter((r) => r.status === 'FAILED').length;