Fix Focus Mode button malfunction on first launch

[mirka]

There was a bug where the Focus Mode toggle button would not work immediately after launching the app. This was happening because the is-note-open CSS class was not being set correctly.

Steps to reproduce

1. Log in
2. Quit and relaunch app (or reload browser)
3. Click Focus Mode toggle button

→ Nothing happens

To test

Try the above steps, and verify that the Focus Mode toggle button works as expected.

[roundhill]

Try the above steps, and verify that the Focus Mode toggle button works as expected.

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