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

cmd/root.go

@@ -10,6 +10,7 @@ import (
 	"github.com/unclesam-ly/git-air/internal/llm"
 	"github.com/unclesam-ly/git-air/internal/reviewer"
 	"github.com/unclesam-ly/git-air/internal/ui"
+	"github.com/unclesam-ly/git-air/internal/updater"
 )
 
 var rootCmd = &cobra.Command{
@@ -21,6 +22,9 @@ var rootCmd = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 		ctx := cmd.Context()
 
+		// 后台非阻塞异步检查新版本
+		updateCh := updater.CheckAsync()
+
 		// 1. 检查并获取 Diff
 		if flagCached, _ := cmd.Flags().GetBool("cached"); flagCached {
 			args = append([]string{"--cached"}, args...)
@@ -96,7 +100,16 @@ var rootCmd = &cobra.Command{
 
 		ui.PrintFooter()
 
-		// 8. 门禁阻断检测 (Pre-commit 拦截逻辑)
+		// 8. 检查新版本提醒（非阻塞）
+		select {
+		case info := <-updateCh:
+			if info != nil {
+				ui.PrintUpdateBanner(info.CurrentVersion, info.LatestVersion, info.ReleaseURL)
+			}
+		default:
+		}
+
+		// 9. 门禁阻断检测 (Pre-commit 拦截逻辑)
 		outText := reviewOutput.String()
 		hasBlocker := strings.Contains(outText, "[BLOCKER]") || strings.Contains(outText, "[CRITICAL]")
 		hasReject := strings.Contains(outText, "[REJECT]")

cmd/update.go

@@ -0,0 +1,35 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+
+	"github.com/spf13/cobra"
+	"github.com/unclesam-ly/git-air/internal/ui"
+	"github.com/unclesam-ly/git-air/internal/updater"
+)
+
+var updateCmd = &cobra.Command{
+	Use:     "update",
+	Aliases: []string{"upgrade"},
+	Short:   "一键升级 git-air 到最新版本",
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Printf("🔍 正在检查并拉取最新版本 (当前: %s)...\n", updater.CurrentVersion)
+
+		updateCmd := exec.Command("go", "install", "github.com/unclesam-ly/git-air@latest")
+		updateCmd.Stdout = os.Stdout
+		updateCmd.Stderr = os.Stderr
+
+		if err := updateCmd.Run(); err != nil {
+			ui.PrintError("升级失败: %v (提示: 请确保已安装 Go 并配置环境变量)", err)
+			return
+		}
+
+		ui.PrintSuccess("git-air 已成功升级至最新版本！🎉")
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(updateCmd)
+}

cmd/version.go

@@ -0,0 +1,38 @@
+package cmd
+
+import (
+	"fmt"
+	"runtime"
+
+	"github.com/spf13/cobra"
+	"github.com/unclesam-ly/git-air/internal/ui"
+	"github.com/unclesam-ly/git-air/internal/updater"
+)
+
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "查看当前 git-air 版本信息及更新检测",
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Printf("git-air %s (%s/%s, Go %s)\n",
+			updater.CurrentVersion,
+			runtime.GOOS,
+			runtime.GOARCH,
+			runtime.Version(),
+		)
+
+		checkFlag, _ := cmd.Flags().GetBool("check")
+		if checkFlag {
+			info := updater.CheckUpdate(true)
+			if info != nil {
+				ui.PrintUpdateBanner(info.CurrentVersion, info.LatestVersion, info.ReleaseURL)
+			} else {
+				ui.PrintSuccess("当前已是最新版本！")
+			}
+		}
+	},
+}
+
+func init() {
+	versionCmd.Flags().BoolP("check", "c", true, "向 GitHub 检查是否有可用新版本")
+	rootCmd.AddCommand(versionCmd)
+}