Add Multi-language Support

[pmady]

Description

Add internationalization (i18n) support for non-English speakers.

Requirements

• Support for major languages (Spanish, Chinese, Japanese, Portuguese, German)
• Language switcher in navigation
• Translated content for key sections
• Community contribution workflow for translations

Acceptance Criteria

• i18n plugin configuration for mkdocs
• Language selector in header
• At least 2 languages fully translated
• Translation contribution guide
• Automated translation status tracking