docs: add Russian(RU) translation of README

[whonion]

✨ Added complete Russian (RU) translation that:

Maintains original document structure and layout Preserves all formatting, emojis, and technical terms Retains all original links and image references Includes full translation of all sections (Features, Use Cases, Quick Start, etc.) Updates language selector in Translations section Purpose 🌍 This translation is part of our internationalization efforts to make Eliza more accessible to Russian-speaking developers.