Add course documentation and demo stack

[bihius]

Summary

• add a Polish course project report covering architecture, API, database, auth, CRUD, frontend, demo, and screenshot placeholders
• add a deploy/demo stack with two echo applications behind HAProxy/Coraza
• add demo setup automation for admin seeding, policy/vhost creation, config apply, temporary self-signed TLS, and CRS presence checks

Validation

• bash -n deploy/demo/setup-demo.sh
• docker compose --env-file deploy/demo/.env -f deploy/demo/docker-compose.yml config

Notes

• demo requires OWASP CRS submodule initialization before startup
• temporary TLS bind is demo-only and can be overwritten by a later config apply

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