Add a new GH Actions job to automatically update translated document pagse

[seratch]

This pull request adds a new GitHub Actions job to automate the translation of document pages.

• Before this job can run, OPENAI_API_KEY must be added to the project secrets.
• It typically takes 8–10 minutes using the o3 model, so the job is configured to run only when there are changes under docs/ or in mkdocs.yml.
• The job commits and pushes the translated changes, but it does not deploy the documents to GitHub Pages. If we think it’s better to deploy the latest changes automatically as well, I’m happy to update the workflow. (Personally, I don’t think it’s necessary, since the changes will be deployed with the next deployment job execution)

[rm-openai]

possible to only add changes in docs? Just to prevent other stuff from slipping in?###