Fix non-deterministic cell death in preview mode by resetting lastUpdate on load

[Copilot]

Cached phenotype data carries non-zero lastUpdate values from previous preview runs. Combined with arbitrary _currentTimestep % 100 alignment relative to the head update cycle, cells can accumulate lastUpdate > 201 before receiving a head update propagation, triggering CellState_Dying at CellProcessor.cuh:143. The non-determinism stems from variable timestep phase and frame-dependent cache extraction timing.

Changes

• EngineWorker::setPreviewData: Reset lastUpdate = 0 for all cell objects in the TO before GPU upload, ensuring 202 timesteps of headroom for head update propagation regardless of cached state
• DataTransferTests.objectsWithEmptyGenomes_preview: Adjust expected lastUpdate to 0 in preview roundtrip comparison, reflecting the intentional reset

auto numObjects = *dataTO.numObjects;
for (uint64_t i = 0; i < numObjects; ++i) {
    if (dataTO.objects[i].type == ObjectType_Cell) {
        dataTO.objects[i].typeData.cell.lastUpdate = 0;
    }
}

---

⌨️ Start Copilot coding agent tasks without leaving your editor — available in VS Code, Visual Studio, JetBrains IDEs and Eclipse.