增加AI页面在其它页面的展示

client/src/hooks/useIsLgUp.ts

@@ -0,0 +1,20 @@
+import { useEffect, useState } from "react";
+
+/** Matches Tailwind `lg:` (1024px). Used for desktop-only UI such as the AI split panel. */
+export function useIsLgUp() {
+  const [lgUp, setLgUp] = useState(
+    () =>
+      typeof window !== "undefined" &&
+      window.matchMedia("(min-width: 1024px)").matches,
+  );
+
+  useEffect(() => {
+    const mql = window.matchMedia("(min-width: 1024px)");
+    const sync = () => setLgUp(mql.matches);
+    mql.addEventListener("change", sync);
+    sync();
+    return () => mql.removeEventListener("change", sync);
+  }, []);
+
+  return lgUp;
+}