fix(webui): remove eager markdown preload

Remove the eager preloading of markdown/code-highlighting chunk at startup.
The markdown renderer will now only be loaded when actually needed to render content.

webui/src/App.tsx

@@ -5,7 +5,7 @@ import { Sidebar } from "@/components/Sidebar";
 import { SettingsView } from "@/components/settings/SettingsView";
 import { ThreadShell } from "@/components/thread/ThreadShell";
 import { Sheet, SheetContent } from "@/components/ui/sheet";
-import { preloadMarkdownText } from "@/components/MarkdownText";
+
 import { useSessions } from "@/hooks/useSessions";
 import { useTheme } from "@/hooks/useTheme";
 import { cn } from "@/lib/utils";
@@ -157,22 +157,7 @@ export default function App() {
     return bootstrapWithSecret(saved);
   }, [bootstrapWithSecret]);
 
-  useEffect(() => {
-    const warm = () => preloadMarkdownText();
-    const win = globalThis as typeof globalThis & {
-      requestIdleCallback?: (
-        callback: IdleRequestCallback,
-        options?: IdleRequestOptions,
-      ) => number;
-      cancelIdleCallback?: (handle: number) => void;
-    };
-    if (typeof win.requestIdleCallback === "function") {
-      const id = win.requestIdleCallback(warm, { timeout: 1500 });
-      return () => win.cancelIdleCallback?.(id);
-    }
-    const id = globalThis.setTimeout(warm, 250);
-    return () => globalThis.clearTimeout(id);
-  }, []);
+
 
   if (state.status === "loading") {
     return (

webui/src/components/MarkdownText.tsx

@@ -10,9 +10,7 @@ interface MarkdownTextProps {
 const loadMarkdownRenderer = () => import("@/components/MarkdownTextRenderer");
 const LazyMarkdownRenderer = lazy(loadMarkdownRenderer);
 
-export function preloadMarkdownText(): void {
-  void loadMarkdownRenderer();
-}
+
 
 /**
  * Lightweight markdown renderer mirroring agent-chat-ui: GFM + math via