- Dockerfile.web: two-stage build (builder + production), non-root appuser
- docker-compose.yml: MySQL healthcheck, depends_on service_healthy,
  explicit backend/frontend networks, Adminer under dev profile
- README.md: full rewrite with architecture diagram, compose instructions,
  config table — English and Russian
- CHANGES.md: educational breakdown of each improvement with examples
- .env.example: cleaned up duplicates and removed leftover WEBAPP_URL

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