Use npm ci in the Dockerfile. Closes #840

[regulartim]

Description

This changes the way we install frontend dependencies in order to create reproducible builds. We already use npm ci in .github/workflows/_node.yml.

Related issues

• Docker frontend stage does not create reproducible builds #840

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist

• I have read and understood the rules about how to Contribute to this project.
• The pull request is for the branch develop.
• I have added documentation of the new features.
• Linter (Ruff) gave 0 errors. If you have correctly installed pre-commit, it does these checks and adjustments on your behalf.
• I have added tests for the feature/bug I solved. All the tests (new and old ones) gave 0 errors.
• If changes were made to an existing model/serializer/view, the docs were updated and regenerated (check CONTRIBUTE.md).
• If the GUI has been modified:
  • I have a provided a screenshot of the result in the PR.
  • I have created new frontend tests for the new component or updated existing ones.

Important Rules

• If you miss to compile the Checklist properly, your PR won't be reviewed by the maintainers.
• If your changes decrease the overall tests coverage (you will know after the Codecov CI job is done), you should add the required tests to fix the problem
• Everytime you make changes to the PR and you think the work is done, you should explicitly ask for a review. After being reviewed and received a "change request", you should explicitly ask for a review again once you have made the requested changes.

[mlodic]

good catch, that's the recommended way in Dockerfiles