Hwaro::Models::Config::SectionLoader

One entry per section loader: the top-level config.toml key(s) it reads and the loader itself. This is the registry a new section joins (see src/models/config/*.cr) — it drives both the load order and the unknown-key warning, so a section can't be loaded without also being recognised, or vice versa.

Order matters for exactly four entries: languages reads the menus and taxonomies already loaded (per-language overrides), sass reads auto_includes, resolve_deployment_source_dir reads build and deployment, and the search facet check reads the taxonomies. Everything else only reads config.raw.