v1.1.0 - Domain Exception Architecture

- Refactored exceptions from service_layer to domain layer
- Pure Python domain exceptions (no HTTP coupling)
- Explicit HTTPException conversion in API routes
- Hexagonal Architecture compliance improvement

- Import path changed: `domain.exceptions` instead of `service_layer.exceptions`
- ServiceError removed, use DomainError as base class

Release v1.0.0: VOID - DDD + Hexagonal Architecture FastAPI Boilerplate