Run airport/airline imports on startup and weekly (AVI-43)

[cfarrell987]

Summary

• Web now runs import_airports --yes and import_airlines --yes on every container startup (after migrate, before gunicorn). Both commands are already idempotent (skip existing, sync disabled/re-enabled), so this only ever adds new rows.
• A new scheduler service (ofelia, docker-native cron) re-runs the same two commands weekly via docker exec against the web container, driven by ofelia.job-exec.* labels on web.
• If an import fails on startup (e.g. no network), it's logged but doesn't block gunicorn from starting.

Went with ofelia over Celery+Beat+Redis since there's no task-queue infra in the repo yet and this is just two weekly jobs — ofelia adds zero new Python dependencies, it's config-only.

Test plan

• docker compose up -d --build from clean volumes: confirmed web logs show migrate → import_airports (3953 new) → import_airlines (1019 new) → gunicorn boot, in order
• scheduler container logs show both jobs registered: import-airports and import-airlines, schedule @weekly
• Verified via psql that airports_airport (3953 rows) and airlines_airline (1019 rows) are populated
• Manually ran the exact scheduled commands via docker exec against the running web container (simulating what ofelia does) — confirmed idempotent re-run: 0 new rows, no errors