CSV import/export
Download current matches. CSV upload currently validates file format only; online bulk import still needs an admin-only server action before it can write to Supabase.
CSV upload validates headers and rows, but it does not write to Supabase yet. Do not use it for production migration until the dedicated online import action is implemented.
Calculated league data
Replay every canonical match to refresh player ratings, standings, avatars, snapshots, and match details. Run this after importing SQL.