Update long term exercise screens correctly

[ztefanie]

Describe the Bug

• Fix the navigation bar badge: After finishing exercises or adding new words, the badge is not always updated correctly.
• Fix the navigation to the repetition screen, should always be updated, not working correctly.

Steps to Reproduce

• Add new words to the repetition exercise. See both the footer and the screen are not updated as expected. When closing and reopening the app, the view is displayed correctly.

Expected Behavior

Screen and badge are updated immediately

Actual Behavior

Screens do not update

[david-venhoff]

Looks like the main problem is that our async store is not reactive. The current workaround is that we just refresh values from the store every time a focus event happens, which seems to go wrong here somehow.

Maybe a more robust solution would be to switch to something like https://github.com/ammarahm-ed/react-native-mmkv-storage?

[david-venhoff]

Actually, I can only reproduce this issue when I add words with the devtools to fill the repetition excercise with data. So it is rather low prio imo

[david-venhoff]

For future reference, I have create a proof of concept branch that switches to reactive sync storage, which avoids the need for any focus effect hacks: experiment/sync-storage