- split settings module into per-struct files
- add DatabaseSettings with default in-memory SQLite path
- implement RelayApi struct with GET /relays and POST
/relays/{id}/toggle
- wire create_relay_controller and create_label_repository into
Application::build() with mock/real selection via cfg!(test) || CI
- register RelayApi in OpenApiService alongside existing APIs
Add GetAllRelaysUseCase (T043) for retrieving all 8 relay states with
labels, coordinating controller reads and repository label lookups
with comprehensive error handling and logging.
Implement ToggleRelayUseCase (T041) for toggling individual relay
states with read-before-write pattern, state validation, and label
retrieval.
Add use_cases module (T044) with trait-based dependency injection for
testability, exposing both use cases for presentation layer
integration.
Comprehensive test coverage includes 7 toggle tests (state
transitions, error handling, double-toggle idempotency) and 9 get-all
tests (count, ordering, state correctness, label inclusion, error
scenarios).
Ref: T041 T042 T043 T044 (specs/001-modbus-relay-control/tasks.org)
phundrak
