Phase 2 created cloud instances without recording who owns them on this
side, because the collection did not exist. The boot backfill reconstructs
one member row per instance from the hq-sourced control-plane owner, and
marks every existing customer_user an owner — they all created their own
account.
Backfill lives in models rather than db: db is the connection layer and
models already imports it for SeedPlans, so db -> models would cycle.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>