feat: implement db helpers and postgres pool/transactor
- Add is_blocked to core.users (002_core_tables.sql)
- Add is_active to activity.sessions for soft deletes (005_activity_tables.sql)
- Implement UserRepo: List, GetByID, GetByName, Create, Update, Delete
- Implement MimeRepo: List, GetByID, GetByName
- Implement SessionRepo: Create, GetByTokenHash, ListByUser,
UpdateLastActivity, Delete, DeleteByUserID
- Session deletes are soft (SET is_active = false); is_active is a
SQL-only filter, not mapped to the domain type
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Masahiko AMANO
f7cf8cb914