portuguese support

MathJax does not currently support the Portuguese language. As a mathematics educator and researcher in Brazil, I often need to present mathematical content in Portuguese for my students and colleagues. Unfortunately, the lack of Portuguese support in MathJax creates significant barriers to accessibility and usability for Portuguese-speaking users.

I would like to see full support for the Portuguese language in MathJax, including localization for UI elements, error messages, and documentation. This would make MathJax much more accessible for the Portuguese-speaking mathematics and education community.

I have considered manually translating some interface elements or error messages, but this approach is not scalable and does not address the need for official and complete Portuguese localization support within MathJax itself.

I am willing to contribute to the project to help bring Portuguese language support to MathJax. Please let me know how I can collaborate with the development team or start working on this feature.

The issue names no files, tests, or entry points. Start by locating MathJax's existing localization resources and the systems for UI elements, error messages, and documentation, then compare how another supported language is organized. Done should mean Portuguese coverage is implemented across the stated areas and verified through the project's relevant checks.