- Implemented `InvoicingPeriodDraftOverlayTest` with coverage for blocking and permitting invoicing actions based on draft states, transactions, and metadata.
- Created `ReferenceSuggestionsApiTest` to validate ranked and filtered suggestions across bookings, orders, and vehicles with varied match relevance, context, and frequency.
- Added `order_reference_suggestions_service` class, including query methods, normalization utilities, and aggregation logic for reference suggestions.
- Enhanced query handling in `InvoicingPeriodDraftOverlayFakeDb` to validate SQL constraints and column cache resets in overlapping invoicing contexts.