Allow to easily check PR impacts on UI

[jeluard]

Investigate solutions to ease PR verifications, notably that no regression gets introduced in the UI.

e.g.

• testing framework with unit tests/screenshot diffs
• deployment per PR for manual inspection

relates to #413

[rolfyone]

Fair, I tend to not actually run things that 'look right', it'd be nice to have more confidence that things wont break (eg. ethereum logo, actually seeing content)