Function project_document_rows 

fn project_document_rows(
    project: ProjectInstanceId,
    generation: IndexGeneration,
    graph: &SymbolGraph,
    facts: &MarkdownFacts,
    owners: &GraphOwners,
    document_index: &DocumentResolutionIndex<'_>,
    candidates: &ProjectResolutionRegistry,
    staged_entities: &BTreeMap<String, GraphEntity>,
    control: &IndexWorkControl,
) -> Result<ProjectedGraphRows, CliError>

Project one Markdown fact batch into canonical document relations and coverage.