Add Status filter for deleted tasks

### Describe your improvement idea or feature request

Currently the deleted tasks are shown in the filter when COMPLETED status is selected.
There can be a separate status filter for DELETED to provide more clarity.

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

1. Add a deleted status filter.
2. Don't show deleted tasks in completed filter.

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

_No response_

### How can we contact you (optional)

_No response_

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

Yes

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

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

Start by locating the task status filter and the mapping for COMPLETED and deleted tasks in the Flutter app. Check how the filter is presented and how tasks are classified, then verify that DELETED is selectable separately and deleted tasks no longer appear under COMPLETED.

Rédigé par le modèle d'indexation à partir du texte de l'issue.