Build Docker image on slim base (#3204)

* 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

---------

Co-authored-by: fkwp <github-fkwp@w4ve.de>

.github/workflows/test.yaml

@@ -30,7 +30,7 @@ jobs:
           fail_ci_if_error: true
   playwright:
     name: Run end-to-end tests
-    timeout-minutes: 10
+    timeout-minutes: 30
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
@@ -49,9 +49,9 @@ jobs:
           docker compose -f playwright-backend-docker-compose.yml -f playwright-backend-docker-compose.override.yml pull
           docker compose -f playwright-backend-docker-compose.yml -f playwright-backend-docker-compose.override.yml up -d
           docker ps
-      - name: Copy config file
-        run: cp config/config.devenv.json public/config.json
       - name: Run Playwright tests
+        env:
+          USE_DOCKER: 1
         run: yarn playwright test
       - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         if: ${{ !cancelled() }}