Add AGENTS.md with development environment setup instructions

[linkinpark911]

Summary

Adds AGENTS.md with Cursor Cloud specific instructions for developing in this static-asset localization repository.

Changes

• Created AGENTS.md documenting how to run and test the Moot language files locally (serve via HTTP server, open test.html?<lang_code> in browser)
• Documented important caveats: UTF-8 encoding requirement, CDN dependencies, no file:// protocol

Development Environment

This is a pure static-asset repository (JS locale files + test HTML page). No build system, package manager, or automated tests exist. The development workflow is:

1. Start a static HTTP server: python3 -m http.server 8000
2. Open http://localhost:8000/test.html?en (or any language code) in a browser
3. Visually verify translations render correctly

Demo

demo_language_switching.mp4

Language switching between English, Finnish, and Chinese demonstrated working correctly.

Network tab showing en.js loaded successfully

_{To show artifacts inline, enable in settings.}