feat: 新增 Chat 聊天页面并优化 Agents

- 新增 Chat.vue 聊天页面组件
- 重构 Agents.vue 页面代码
- 更新侧边栏和路由配置

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/router/index.ts

@@ -1,6 +1,7 @@
 import { createRouter, createWebHistory } from 'vue-router'
 import Dashboard from '@/views/Dashboard.vue'
 import Login from '@/views/Login.vue'
+import Chat from '@/views/Chat.vue'
 import Agents from '@/views/Agents.vue'
 import Team from '@/views/Team.vue'
 import Skill from '@/views/Skill.vue'
@@ -24,6 +25,11 @@ const router = createRouter({
       name: 'dashboard',
       component: Dashboard
     },
+    {
+      path: '/chat',
+      name: 'chat',
+      component: Chat
+    },
     {
       path: '/agents',
       name: 'agents',