Add Indonesian translation

[temamumtaza]

Summary

This PR adds the Indonesian translation for the Hugging Face Agents Course.

Changes included:

• Add full Indonesian course content under units/id
• Add Indonesian _toctree.yml
• Add Indonesian translation helper script in scripts/id.py
• Add Indonesian translation agreement and glossary in translation_agreements/id
• Add id to the documentation build workflows

Validation

I checked the translation structure locally:

• units/id has the same 78 documentation files as units/en
• units/id/_toctree.yml parses as valid YAML
• Key MDX component counts match the English source
• No trailing whitespace in Indonesian docs
• Code blocks, URLs, paths, package names, API names, and library names were preserved where appropriate

Notes

The translation keeps common AI and developer terms in English where that is more natural for Indonesian readers, following the included translation agreement.