`scripts/seed-large-account.ts` inserts about 1.25 million measurements
for one user, shaped like an Apple Health export plus the iOS sync: dense
heart rate, HRV and SpO2, the high-frequency mean types, export `stats:`
daily rows, recent per-sample cumulative rows and nightly sleep stages.
Everything is generated in Postgres, so a run takes seconds, and it ends
with ANALYZE. It is how the maintenance jobs in #1031 were reproduced and
measured; never point it at a database holding real data.
