Moved the Config struct (previously in internal/models/config.go) into internal/platform/config/types.go to align with clean architecture principles.
This change decouples runtime/infrastructure configuration from domain models:
- Configuration is an application/platform concern, not part of the business domain.
- Prevents potential circular imports between models and platform packages.
- Simplifies future integration with platform components (SCS sessions, CSRF, DB).
No functional changes to configuration loading structure and JSON schema remain the same; only the package location and imports were updated.
