* Build Docker image on slim base
* Run Playwright tests against Docker container
For Playwright end-to-end tests in CI, instead of running a development
webserver with `yarn dev`, build and deploy a Docker container for
Element Call and use that as the webserver to test against.
* Shut down playwright webserver gracefully
When using a containerized webserver, this stops the container once
tests finish.
* Increase Playwright timeout in CI
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Co-authored-by: fkwp <github-fkwp@w4ve.de>
