feat: Add Docker Swarm deployment scripts for zero downtime

- Update docker/docker-compose.yml for Swarm with start-first update order
- Add scripts/deploy-swarm.sh for deploying with separate blog/wallet env files
- Add scripts/rollback-swarm.sh for quick rollback to previous version
- Add .env.blog.example and .env.wallet.example with documented settings
- Add missing REACT_APP_APP_SESSION_TIME to testing env files
- Remove obsolete docker/.env (was unused)