No pull-to-refresh on an empty gallery

[krugerk]

### Desiderata
- [x] Try replicata with modern BeemiOS

Replicata

1. Have a fresh account with no goals
2. Open the BeemiOS app and see "no goals yet!"
3. Go to the website and create a goal
4. Come back to BeemiOS
5. Idle at the gallery which still shows empty without the means to trigger a new fetch there directly.
6. Workarounds: kill the app, launched again; tap about various screens like settings then back to the gallery; log out and back into the app

Expectata

That User I can perform a pull-to-refresh while at the gallery screen to force a fetch of goals.

Resultata

The empty gallery does not provide PTR nor a refresh/retry/refetch button.

Circumventata

Close and reopen the app?

Nota Nebulosa

UI copy:

No goals yet!

In-app goal creation is coming soon, but for now, head to beeminder.com to create a goal.

If the app is not going to receive a push message that a new goal has been created, the gallery when empty should still perhaps allow pull-to-refresh.

Cognata

• hint for no goal when filtering and ptr on empty list #506

Verbata: pull-to-refresh, empty gallery, newbee with no goals,