Implemented plugin for latex compatability

[zenxol]

https://github.com/CMU-313/nodebb-spring-26-kernel-panic/issues/9

Summary

Adds LaTeX/math support to the forum so users can write and render math in new topics and replies.

• Toolbar button: LaTeX (superscript) button in the composer that inserts $$ $$ or wraps the selection with $$...$$.
• Rendering: MathJax 3 loads from CDN when needed and renders inline $...$ and display $$...$$ in the composer preview and in posts.

Changes

• New plugin in vendor/nodebb-plugin-composer-latex/ (library, client scripts, MathJax loader, language file).
• package.json: dependency added for nodebb-plugin-composer-latex (local vendor path).

How to use

1. Create a new topic or reply.
2. Use the LaTeX button (x² icon) or type $...$ (inline) or $$...$$ (display).
3. Preview and published posts will render the math.

Setup for reviewers / after merge

• npm install then ./nodebb build (Redis or DB must be running).
• In Admin → Extend → Plugins, activate Composer LaTeX if it isn’t already active. This is a mandatory step!

Testing

• In the composer, click the LaTeX button and confirm $$ $$ is inserted.
• Type e.g. $$x^2 + y^2 = z^2$$ and use Preview to confirm it renders.
• Post and confirm the same math renders in the topic.

[coveralls]

Pull Request Test Coverage Report for Build 22022403183

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 78.828%

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Totals
Change from base Build 21806455475:	0.0%
Covered Lines:	25357
Relevant Lines:	30331

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💛 - Coveralls