feat: 新增 proc.list/user.list/pkg.list 命令

proc.list 列出所有进程（ps aux/tasklist）
user.list 列出系统用户（getent passwd/net user）
pkg.list 列出已安装软件包（dpkg/rpm/apk/brew/winget）

internal/executor/proclist.go

@@ -0,0 +1,26 @@
+package executor
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+	"runtime"
+)
+
+// runProcList implements `kopsc proc list`: list all processes.
+func runProcList(ctx context.Context, req BuiltinRequest) error {
+	switch runtime.GOOS {
+	case "linux", "darwin":
+		cmd := exec.CommandContext(ctx, "ps", "aux")
+		cmd.Stdout = req.Stdout
+		cmd.Stderr = req.Stderr
+		return cmd.Run()
+	case "windows":
+		cmd := exec.CommandContext(ctx, "tasklist")
+		cmd.Stdout = req.Stdout
+		cmd.Stderr = req.Stderr
+		return cmd.Run()
+	default:
+		return fmt.Errorf("不支持的操作系统: %s", runtime.GOOS)
+	}
+}