Turn off push notifications on logout

[danieldaquino]

Summary

Turn off push notifications during logout to prevent unwanted push notifications.

This is the basic solution, based on a best effort attempt to unsubscribe the user from receiving notifications.

The following has not been implemented/considered:

• Handle edge cases (what if revoking the token fails? What if the user did not have push notifications to start? etc)
• Improve error handling (If things fails, what do we show the user?)
• What if the user already logged out before this change and their npub is still registered on our servers? How can we detect that and revoke?

However, this PR probably solve the problem for most scenarios (probably 90%+), and improves behaviour significantly compared to the current state, so it's worthwhile in my opinion.

Checklist

• I have read (or I am familiar with) the Contribution Guidelines
• I have tested the changes in this PR
• My PR is either small, or I have split it into smaller logical commits that are easier to review
• I have added the signoff line to all my commits. See Signing off your work
• I have added appropriate changelog entries for the changes in this PR. See Adding changelog entries
• I have added appropriate Closes: or Fixes: tags in the commit messages wherever applicable, or made sure those are not needed. See Submitting patches

Test report

Device: iPhone 16 simulator

iOS: 18.1

Damus: 2a2ddb3674159c87490df52efbdc321936e34490

Setup:

1. Staging env for push notifications
2. An extra device and account to trigger push notifications

Steps:

1. Send a DM to the user under test
2. Push notification should be received
3. Logout
4. Repeat step 1
5. Push notification should not appear

Results:

• PASS

[jb55]

one suggestion

[danieldaquino]

@jb55, addressed concerns, and tested the change!