Implement CI checks

[IgorKrupenja]

AS A developer
I WANT to have continuous integration checks
SO THAT I can prevent merging bad code and reduce conflict resolution

Acceptance Criteria

• Upgrade or install the latest versions of ESlint, Prettier and Vitest dependencies for the GUI.
• Add a Vitest config with a simple example test for the GUI.
• Dependabot is implemented as close as possible to this PR.
  • You may need to add package-lock.json to .prettierignore to avoid issues.
• ESLint should be configured as close as possible to this PR:
  • Same rule set in general.
  • All recommended Sonarcloud rules enabled.
  • Skip JS rules config from the linked sample as this repo is TS-only.
  • Add some recommended React-specific rules.
• If there are many linter issues, create a follow-up task to fix these.
• Add CI checks with GitHub Actions that should be configured as close as possible to this PR.
• Old/broken CI workflows are removed.
  • Confirmed with Varmo that the following are safe to remove: ci-build-publish-main.yml, .github/workflows/feature-dev-pipeline.yml, .github/workflows/snyk-security.yml, ‎.github/workflows/sonarcloud.yml.
  • The following workflow is actively used and cannot be removed: check-version.yml.
  • Any other workflows not listed above need to be investigated and removed if not used or broken.
• .prettierrc should be exactly as in this PR. Re-format the codebase if necessary:

{
  "tabWidth": 2,
  "singleQuote": true,
  "printWidth": 120
}