- Add multi-layered entity support for `Turniere`, `Bewerbe`, and `Abteilungen` with tenant isolation.
- Implement Flyway schema migrations with constraints, indices, and default values for `Turniere`.
- Add Kotlin repositories and services for CRUD operations and validation across entities.
- Ensure tenant-safe transactions and implement new exception handling for `LockedException` and `ValidationException`.
- Provide REST APIs with controllers for managing lifecycle, hierarchy, and relationships between entities (`Turniere`, `Bewerbe`, and `Abteilungen`).
- Update Spring configuration with dependency wiring for new services and repositories.