Output Path

Relative path where the materialized artifact should be written by `kanonak site build`, e.g. `about/index.html` or `snapshot@1.0.4/view.html`. Resolved against the `kanonak site build --out <dir>` base directory. If omitted on a StaticPage / ResourcePage, the CLI falls back to `<page-name>.html`; AggregateView requires it explicitly.