Remove the redundant `Source` property from `IRelationship` and its
implementations. Since the relationship component is inherently
stored on the source entity, the `Source` field was unnecessary and
required manual synchronization during deserialization.
This change simplifies the relationship model, reduces memory usage,
and removes the need for reflection-based fixups in the serializer.
- Add xUnit test projects for both games
- Implement game flow tests for Blackjack
- Implement game flow tests for TicTacToe
- Rename namespaces and projects to follow `Game.*` convention
- Add documentation for testing games
hypercross