docs: rewrite README for v2 — English main + Russian translation

Replace 1146-line Russian-only README with two focused files:
- README.md (249 lines, English) — primary documentation
- README.ru.md (367 lines, Russian) — full translation
Both cover v2 features: agent-memory, vault-health, 3-phase pipeline.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: smixs