feat(webui): highlight slash commands and app mentions (#4933)

webui/src/components/thread/ThreadShell.tsx

@@ -238,7 +238,7 @@ function useInstalledSettingItems<Payload, Item>({
       const payload = await fetchPayload(token);
       if (!isCancelled?.()) setItems(selectItems(payload));
     } catch {
-      if (!isCancelled?.()) setItems([]);
+      // Keep the last successful catalog during transient focus/visibility refresh failures.
     }
   }, [fetchPayload, selectItems, token]);
 
@@ -842,6 +842,7 @@ export function ThreadShell({
           showScrollToBottomButton={!!session}
           cliApps={cliApps}
           mcpPresets={mcpPresets}
+          slashCommands={slashCommands}
           forkBoundaryMessageCount={forkBoundaryMessageCount}
           hasMoreBefore={hasMoreBefore}
           loadingOlder={loadingOlder}