Use Playwright for integration tests

We currently use Selenium to test the examples in our documentation for errors. This is useful, but it doesn't catch features silently failing. This happened in our v0.19.0 release.

We need tests that actually verify the expected elements are visible on the page. This requires work: for each example we have to define what elements are expected, possibly after clicking on some other element.

I'd like to try to use Playwright for this. It looks pretty easy to use. It also integrates with Pytest. I'll give this a shot on a couple examples to see if this approach works well. If so, we can apply it to all examples.

Comienza revisando las pruebas de integración existentes basadas en Selenium para los ejemplos de la documentación y cómo se ejecutan con Pytest. Prueba Playwright con un par de ejemplos, definiendo los elementos visibles esperados y cualquier clic necesario. La tarea está terminada cuando el enfoque detecta funcionalidades que fallan silenciosamente y puede aplicarse de forma coherente a todos los ejemplos.