Support annotations

### Describe your improvement idea or feature request

a Taskwarrior task can have any number of annotations, and it's great to be able to associate notes on a task, beyond the description. This feature request is to extend that functionality to taskwarrior-flutter.

### How would you like to see it implemented?

1. expose an annotation field in the task details view, with a button for New Annotation.
2. If the task has annotations, display each one at the bottom of the task details view.
3. on clicking New Annotation button, or existing annotation, open in a simple edit window (markdown supported?)
4. sync tasks with annotations, as usual.

### Put here any screenshots or videos (optional)

screenshots to follow

### How can we contact you (optional)

_No response_

### Would you like to work on this issue?

None

### By submitting this issue, I have confirmed that:

- [X] I have starred the repo ⭐ and watched 👀 it on GitHub and followed the contribution guidelines.

タスク詳細ビューとタスク同期フローから始め、次にタスクフィールドがどのように表現されているかを確認します。要求された New Annotation と既存のアノテーション用のエントリーポイントを通じて、アノテーションの表示と編集を追加し、アノテーションがタスクと同期されることを保証します。タスクでアノテーションを表示、作成、編集でき、同期が維持されれば完了です。

索引モデルが issue の本文から書いたものです。