Implement CommandZoneLogic - the card data management layer for zones.
This layer handles card insertion, removal, and ordering independently
of Qt graphics rendering.
Key components:
- CommandZoneLogic: manages card data within a zone
- AddCardAlgorithm: generic insertion algorithm for ordered zones
- CardZoneLogic modifications: integrate with existing zone hierarchy
Design decisions:
- Separation of data logic from graphics enables unit testing
- addCardImpl uses a stable insertion algorithm for consistent ordering
- Mock card items enable testing without Qt graphics dependencies
Test coverage verifies card insertion behavior across edge cases.
