Add e2e tests

[andtos90]

The app has no e2e tests and it's difficult to validate the correctness of each change and avoid regressions. We should investigate how to add e2e tests. I suggest trying Playwright

• [x] Initial setup (part of #161)
• [x] Make it work with Metamask (Part of #161)
• [ ] Make it work on the CI
• [ ] Add more tests