feat: Full Russian localization

[cubtok]

This PR introduces full Russian localization for the GoClaw documentation site.

Key changes:

• Translated all 119+ documentation pages into Russian (located in the /ru/ directory).
• Updated the frontend (index.html and js/docs-app.js) to support the RU locale.
• Localized the sidebar navigation and UI strings.
• Updated README.md and package.json with Russian language support.
• Configured the build system (build-llms.js) to generate Russian text artifacts.