- install.sh: deploy binary, config, errors, modules, ssl, run, lib,
  geoip into a single /opt/haproxy/ directory tree
- haproxy.cfg: update all paths (pidfile, socket, errorfile, module-path,
  certs, geoip, server-state, admin socket) to /opt/haproxy/
- haproxy.service: point ExecStartPre/ExecStart/ExecReload to
  /opt/haproxy/haproxy and /opt/haproxy/conf/haproxy.cfg
- .gitlab-ci.yml: adapt test stage to /opt/haproxy/ layout
- test-deploy.sh: update paths for validation
- README.md: document new /opt/haproxy/ directory structure