Support Running Without Triggering npm pack | postbuild support

# Description:

It would be helpful to allow the tool to run directly on the current folder without automatically triggering `npm pack`.

# Use Case:

I want to use this tool as part of a `postbuild` script. However, the current behavior causes an infinite loop:

- `npm postbuild` triggers `attw`
- `attw` triggers `npm pack`
- `npm pack` triggers `npm build`
- `npm build` triggers `npm postbuild`
- ...and the cycle **repeats**

# Current Workaround:

To avoid this loop, I manually create a tarball and run `attw` on it:
```
"postbuild": "tar -czf dist/archive.tgz LICENSE README.md dist/cjs dist/esm dist/umd docs package.json && npx attw --format ascii dist/archive.tgz && rm dist/archive.tgz"
```

# Proposed Solution:

Introduce an option or flag to allow `attw` to operate directly on the current directory without invoking `npm pack`.

まず、npm pack を呼び出す attw CLI のパスを特定し、コマンドラインオプションがどのように解析されるかを確認します。attw が npm pack を呼び出さずにカレントディレクトリを解析でき、postbuild スクリプトから実行してもビルドループを発生させないようになれば、変更は完了です。

索引モデルが issue の本文から書いたものです。