UI mockups: introducing task_info and improving task_edit

### Describe your improvement idea or feature request

Often I'm tapping on a task to see it's details, without necessarily modifying anything. The task edit view is kind of lousy for that, as details are spread apart and span more than one screen. This set of mockups is a suggestion to address that. I would propose that on selecting a task from the task list, goes to task info view, and then, tapping on task details, goes to task edit view. On saving changes, the user should land back in task info (see changes summarized) then back to the list.
I've also illustrated a UI to create, view and edit annotations ( #382 ) although a simple text editor would be desirable.

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

tedious UI fiddling

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


### 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.

まず、既存のタスクリスト、タスク編集ビュー、タスクの選択と保存のナビゲーションを確認し、添付された task_info モックアップと比較します。完了条件は、タスクを選択すると独立した情報ビューが開き、詳細から編集に進め、保存すると変更内容の要約とともにタスク情報に戻り、ナビゲーションからリストに戻れることです。

索引モデルが issue の本文から書いたものです。