- Add RelationType and TransmitterProfession models with two-way sync
- Add migrations 0063 and 0064 for relation types and professions seeding and data migration
- Register RelationType admin serializer, viewset and URL routes
- Update relational migration roadmap documentation
- Introduce TransmitterFeature model with title, slug, and timestamps
- Link features relation to Transmitters and BookAuthors
- Add DovodiTransmitterFeatureViewSet and register routes in admin router
- Add migration 0060 to create table and populate from existing features data
- Update RELATIONAL_MIGRATION_ROADMAP.md with completed features migration
- Add City model and connect origin_city, lived_in_city, and died_in_city to Transmitters and BookAuthors
- Connect city_of_publication_city to BookEdition
- Add Kunya model and connect many-to-many kunyas relation to Transmitters
- Implement DovodiCityViewSet and DovodiKunyaViewSet and register routes in admin router
- Add migrations 0057, 0058, and 0059 to create tables and migrate existing string/JSON data