On startup, reads SSH public keys from two sources:
- UPTOP_ADMIN_KEY env var (single key, quick setup)
- UPTOP_KEYS file path (authorized_keys format, team setup)
Keys already in the database are skipped (idempotent across restarts).
All seeded users get admin role. Username parsed from key comment.
Dockerfile already sets UPTOP_KEYS=/data/authorized_keys — Docker users
just drop their keys file in ./data/ and start the container.