Feature: Add Workflow for Manual Version Bump

We should add a GitHub Actions workflow powered by [**Universal Version Bump**](https://github.com/marketplace/actions/universal-version-bump).
This will allow maintainers to manually trigger version bumps from the **Actions** tab, keeping the project version consistent and reducing manual errors.

## ✅ Acceptance Criteria
- [ ] A workflow is visible in the **Actions** tab.
- [ ] You can choose the bump type (`patch`, `minor`, `major`).
- [ ] Running the workflow updates the version automatically using [**Universal Version Bump**](https://github.com/marketplace/actions/universal-version-bump).
- [ ] (Optional) Extend the workflow later to include Git tagging + release creation.

## 🌟 Why This Matters
- Keeps project versions aligned with development progress.
- Reduces manual overhead and error-prone version edits.
- Leverages [**Universal Version Bump**](https://github.com/marketplace/actions/universal-version-bump) for reliable and consistent updates.
- Lays foundation for future enhancements like automated tagging, changelog updates, and releases.

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🙋 If you’d like, I can open a PR to add this workflow.

まず、リポジトリの GitHub Actions workflow 設定と Universal Version Bump action のドキュメントを確認します。patch、minor、major の選択肢を持つ手動でトリガー可能な workflow を追加し、その後、実行によってプロジェクトのバージョンが更新され、Actions タブに表示されることを確認します。

索引モデルが issue の本文から書いたものです。