PF-2383 Upgrade to Node 24 (with lint setup fixes)

[andreasbalevik]

This ensures the repo is compatible with the upcoming deprecation of Node 20 in GitHub Actions runners: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/.

This contains more changes than just Node 24 upgrades, but we've decided to fix it all as part of upgrading Node so that we only have to create a single release.

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Node 24 changes

• package.json is updated to require Node 24 where applicable
• action.yml is updated to use Node 24 where applicable
• Actions pulled in via composite steps are upgraded to Node 24-compatible versions
  • This required quite big changes for certain actions like in the Slack action

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Lint

• Consolidate linting to fix the discrepancies between local testing and pipeline testing (this means dropping super-linter and using npm run lint in pipeline as well)
• Add pre-commit hook to lint changed files (workflow checks all files)
• Upgraded actions in all lint/test workflows

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Other changes

• The Slack action needed quite a lot of changes to work with the new versions, so we snuck in some QoL updates
  • Color support
  • Avoid adding links to Jira for empty jira-id, or if jira-id is Dependabot
  • Avoid adding links to PR, if pr-number is empty
• Most actions had invalid input configuration as type is not allowed for composite actions. These are removed
• Added description for all inputs as this is best practice
• Upgraded actions

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Testing

• Verify PR title: https://github.com/felleslosninger/plattform-test-app/actions/runs/25672172045/job/75360071026
• Actionlint: https://github.com/felleslosninger/plattform-test-app/actions/runs/25672104899/job/75359825490
• Slack notification (success): https://github.com/felleslosninger/plattform-test-cd/actions/runs/25694541045/job/75439375278
• InfluxDB update: https://github.com/felleslosninger/plattform-test-cd/actions/runs/25694541045/job/75439375261
• Update changelog: https://github.com/felleslosninger/plattform-test-cd/actions/runs/25694541045/job/75439375207
• Get release notes: https://github.com/felleslosninger/plattform-test-cd/actions/runs/25694541045/job/75439375183
• Publish release notes: https://github.com/felleslosninger/plattform-test-cd/actions/runs/25694541045/job/75439375183
• Generate token: https://github.com/felleslosninger/plattform-test-cd/actions/runs/25694541045/job/75439375183
• Slack notification (fail): https://github.com/felleslosninger/plattform-test-cd/actions/runs/25666407777/job/75339996762
• Upgraded linter action: https://github.com/felleslosninger/github-actions/actions/runs/25696628763/job/75446388757
• Upgraded jest action: https://github.com/felleslosninger/github-actions/actions/runs/25696913259/job/75447328900
• Upgraded bats action: https://github.com/felleslosninger/github-actions/actions/runs/25696908435

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After merge

• Create new release
• Update all use of actions from this repo to the new version