feat:重构UI模块

lib/models/layout.dart

@@ -1,13 +1,12 @@
 import 'package:flutter/material.dart';
 
-/// 导航栏
-class NavItem {
+class PageInfo {
   final String label;
   final IconData icon;
   final IconData activeIcon;
   final Widget page;
 
-  const NavItem({
+  const PageInfo({
     required this.label,
     required this.icon,
     required this.activeIcon,