* 2fa qrcode fixes
- add light background to qr code when using dark theme
- show OTP secret code under qr code for manual entry on apps if required
fixes#2386fixes#2389
* fix code formatting
* revert changes re visible code
This conflicts with an existing PR.
* i code pretty
Adds a sass file based on the v10.0.0 Shepherd CSS. Original Shepherd styles are kept where appropriate, otherwise this is intended to inherit whatever styles are being used through the Bulma and Bookwyrm SASS, so that it uses appropriate colours in both light and dark modes.