Cancel button in camera view when adding photo to observation doe not render properly

[achou11]

Issue resides in https://github.com/digidem/comapeo-mobile/blob/8e2863ca63dfad8c9419528ba99c997e282f1ec9/src/frontend/screens/AddPhoto.tsx. Need to apply the background color to the text, not the touchable.

Reproduction steps

1. start observation creation

2. press "add photo" button

What actually happens:

The button is basically a thin rectangle at the bottom of the screen

Expectation:

Should be a thicker red rectangle with the appropriate copy. Here's a screenshot from Mapeo