Unsubmitted datapoint value changes when leaving and coming back to the app

[dreeves]

### Desiderata
- [ ] Replicata or just confirm what Justin experienced is true for everyone
- [ ] Make a guess as to hard this is dev-wise
- [x] Theo just fixes it (part of v6.6)
- [x] Tweet the UVI on 2024-04-02

Message from Justin Hong in support from 2023-09-02 with details and even video proof!

First let's see if we can replicate this easily ourselves by typing a value for a datapoint, then swapping back and forth to another app before coming back to submit the datapoint.

Cognata

• https://secure.helpscout.net/conversation/2349608296/162520?folderId=2972058 (internal link)

• 442 (PR FOR THIS)

• http://beeminder.com/changelog#4825 (THIS UVI)

Verbata: not losing what the user typed,

[theospears]

I believe this was fixed by #442.