[LOW] ci: stop exporting GitHub token to lint job

[OskarEichler]

Summary

Remove the lint job-wide GITHUB_TOKEN environment variable.

Security impact

The job-level export makes the token available to dependency installation, project lint scripts, and the production audit step even though none of them needs it. This unnecessarily increases the impact of a compromised dependency or script.

wagoid/commitlint-github-action already defaults its token input to ${{ github.token }}, so commit linting retains access without exporting the credential to sibling steps.

Verification

• confirmed the pinned action’s action.yml supplies ${{ github.token }} as its default token input
• workflow YAML parses successfully
• git diff --check passes

This PR addresses only the job-wide credential exposure.