Render a saved report. Stored parameters are the base; query parameters override them (so a saved YTD report can be previewed as MTD without editing it).

Renderer-neutral report document (ITE-219). Providers build one of these from metrics queries; the PDF/CSV renderers and the web viewer consume it. Values stay raw and typed — display formatting (whole dollars, "23 min", "No data yet") lives exclusively in ReportValueFormatter per the v4 export spec (docs/reporting-spec-v4/).