feat(updater): 引入 24 小时静默更新检测与一键升级功能

- 新增 `updater` 模块实现 GitHub Release 版本异步检查与本地缓存
- 新增 `git air update` 与 `git air version` 命令支持一键升级及版本检查
- 优化 CLI 终端交互，在首页渲染时提供友好的新版本升级提示卡片

README_EN.md

@@ -211,6 +211,20 @@ git air hook uninstall
 
 ---
 
+### 5. Version Check & One-Click Upgrade (`git air update`)
+
+`git-air` comes with **lightweight 24-hour background update detection** and alerts you in the terminal whenever a new release is available. You can also manually check or upgrade anytime:
+
+```bash
+# Check current version and check for updates
+git air version
+
+# One-click upgrade to the latest release
+git air update
+```
+
+---
+
 ## ⚙️ Configuration Hierarchy
 
 `git-air` searches for configurations in the following priority order: