When CLI options --port/--ws-port were not provided, nil values were
being explicitly passed to Server.start_link, which caused Keyword.get
to return nil instead of the default. Now we only include port options
in the keyword list if they have actual values.
- Add configuration system (config/*.exs, OrgGarden.Config)
- Refactor supervision tree with DynamicSupervisor and Registry
- Add OrgGarden.Server for serve mode lifecycle management
- Add health check HTTP endpoints (Bandit/Plug on :9090)
- Add telemetry events for export and watcher operations
- Implement graceful shutdown with SIGTERM handling
- Add Mix Release support with overlay scripts
- Add NixOS module for systemd service deployment
- Update documentation with service usage
