refactor: 替换管理员登录组件并更新会话管理

src/components/admin/auth-gate.tsx

@@ -0,0 +1,40 @@
+"use client";
+
+import { useRouter } from "next/navigation";
+import { useEffect, useState, type ReactNode } from "react";
+
+import { readToken } from "@/stores/admin-token";
+
+type ShellAuthGateProps = {
+  children: ReactNode;
+};
+
+/**
+ * 壳内路由：仅客户端可读 `localStorage` Token，无 Token 时跳转登录。
+ * 注意：首屏仍可能先出现服务端渲染的页面片段，再完成跳转（未用 Cookie + middleware 前无法完全避免）。
+ */
+export function ShellAuthGate({ children }: ShellAuthGateProps) {
+  const router = useRouter();
+  const [allowed, setAllowed] = useState(false);
+
+  useEffect(() => {
+    const token = readToken();
+    if (!token) {
+      router.replace("/admin/login");
+      return;
+    }
+    queueMicrotask(() => {
+      setAllowed(true);
+    });
+  }, [router]);
+
+  if (!allowed) {
+    return (
+      <div className="flex min-h-[50vh] w-full flex-1 items-center justify-center text-sm text-muted-foreground">
+        正在校验登录状态…
+      </div>
+    );
+  }
+
+  return children;
+}