Run migration (forward-only Drift schema migration)

Apply a schema change to a local Drift/SQLite database by following the exact ordered ritual below. In an offline-first app there is no server and no re-sync path, so the on-device DB is the single source of truth: a migration that drops or corrupts a column permanently destroys hand-entered records that exist nowhere else, and with no telemetry nobody ever reports it — the user just uninstalls. This is a manual, low-freedom, human-run workflow. Execute the steps in order; do not improvise, reorder, or skip.

Non-negotiable rules