Introduce a new database table `department_selfserve_path_confirmations` to store path confirmations related to department configurations. Update `PingApiTest` to verify additional keys, ensuring `backend_version` and `api_commit_sha` are checked in the response.
- Introduce `docker-compose.fleet-host.yml` allowing Elastic Agent to connect to a host-installed Fleet Server.
- Add `pingRoute` to provide a simple `/ping` endpoint returning "pong" with a timestamp.