Android back button behaviour

[Nidwan]

Describe the bug
Despite #91 having been closed, Android back button still doesn't behave as expected : it closes the app no matter which page is displayed.

To Reproduce
Steps to reproduce the behavior:

1. Use Android
2. Go to any child page (like a project)
3. Tap the hardware back button of you device
4. See the app closing instead of going back to the parent page

Expected behavior
It should go back from one child page to the parent page and only close the app from the main page.

Smartphone

• Device: OnePlus 5
• OS: Android 11
• Version Lineage 18.1 Cheeseburger