Explore back pressure for DeterministicWiringModel

The `DeterministicWiringModel` does not support back-pressure, which limits the kind of tests we can run on Turtle. We should explore the possibility of adding this functionality, which would make Turtle even more useful.

Start by locating DeterministicWiringModel and the Turtle tests that are limited by its lack of back-pressure support. Review how the model currently handles test execution and identify the requirements for adding back pressure. Done should be a documented feasibility outcome with a clear scope for implementation.

Written by the indexing model from the issue text.