feat(agent): 实现 Agent 系统并接入 TUI 聊天页面 - #123

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: junka/feishu-bot-webhook-action@main. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/