Function render_migration_report 

pub fn render_migration_report(report: &MigrationReport) -> String

Render the fold report: one line per fold (or would-fold), one loud line per dirty skip, a line per ticket with a NON-terminal sidecar (pipeline state is left sidecar-owned by design), and a summary. No-sidecar tickets are summary-counted only — a line each would drown the signal.