- Removed `install.sh` and moved Docker-related assets to `deploy/docker`.
- Updated all Dockerfile references from `build/` to `deploy/docker/`.
- Refactored paths in E2E tests, Makefile, and documentation for consistency with new directory structure.
- Added `HAPROXY_STATS_CORS_ORIGIN` environment variable in `docker-compose.yml`.
- Updated HAProxy configuration template to set all standard proxy headers for HTTP requests.
- Added support for a unique request ID via `unique-id-format` and `unique-id-header` directives.
- Implemented E2E tests for header validation, request correlation, and configuration correctness.
- Enhanced documentation to explain usage and examples of proxy headers.
- Updated CI workflows to include E2E tests for proxy headers.