Add Russian language support with full documentation

[teslaproduuction]

Summary

This PR adds comprehensive Russian language support to the Humanizer project, including a complete Russian adaptation of the skill with language-specific AI writing pattern detection.

Changes

• README.md: Added link to Russian documentation and new section documenting Russian-specific AI writing patterns (verbal nouns, bureaucratic clichés, etc.)
• README_RU.md (new): Full Russian translation of README with installation instructions, usage guide, and 24+ pattern examples adapted for Russian language
• SKILL_RU.md (new): Complete Russian skill implementation with:
  • Detailed guidance on identifying and removing AI-generated text markers in Russian
  • Russian-specific patterns including отглагольные существительные (verbal nouns) and канцелярит (bureaucratic language)
  • 24+ content, linguistic, stylistic, and communication patterns with before/after examples
  • Emphasis on adding personality and voice to text, not just removing AI markers
  • Full working example showing transformation from AI-sounding to human-written text
  • References to Russian Wikipedia guidelines and Habr research

Key Features

• Language-specific patterns: Addresses unique Russian language characteristics that mark AI-generated text
• Comprehensive examples: All patterns include authentic Russian text examples with before/after comparisons
• Practical guidance: Includes process workflow and output format specifications
• Cultural adaptation: References Russian sources (Wikipedia RU, Habr) rather than just English sources
• Personality focus: Emphasizes that removing AI patterns is only half the work—adding genuine voice is equally important

Implementation Details

The Russian skill maintains feature parity with the English version while adding language-specific guidance for:

• Verbal noun replacement (использование → использовать)
• Bureaucratic phrase simplification (в настоящее время → сейчас)
• Proper Russian quotation marks (« » instead of " ")
• Russian-specific AI vocabulary patterns

All documentation is production-ready and follows the same structure as the English version for consistency.