Buggy save confirmation dialog in details view

### Describe your issue

In the details view when we update a value, it forces us to click "Yes" to save changes.
When we click "No" or "Cancel" it just pops the dialog box and again on back gesture it shows the dialog box until we select "Yes", only then we can go back.
Also in the codebase there is a Snackbar which shows on update which is never shown.

### Steps to reproduce

1. Create task
2. Try updating some value and going back on home page from details page.

### What was the expected result?

1. Go back to homepage when "Yes" or "No" is clicked.
2. Stay on details page when "Cancel" is clicked.
3. Update the values and show Snackbar when "Yes" is clicked.

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

https://github.com/user-attachments/assets/c9833d88-c423-4d0b-9641-ff9aa5dc2b83

### How can we contact you (optional)

[Zulip profile](https://ccextractor.zulipchat.com/#user/848633)

### 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.

詳細ビューの実装から始め、issue に記載されている保存確認ダイアログと既存の Snackbar を追跡してください。記載された手順の更新して戻るフローを再現し、Yes では保存されて Snackbar が表示され、No では保存せずに戻り、Cancel では詳細ページに留まることを確認してください。

索引モデルが issue の本文から書いたものです。