Image-model pass (mocked: no image model is configured on this machine)
1. Control image (segmentation colours, from the data)
2. Line art (walls + props, for a lineart/canny ControlNet)
3. What would come back: a painted image, same size, aligned to the squares
4. In the game: the painted image is only a backdrop; grid, tokens, fog and cover stay drawn from the data on top.