Run only the fermentation and return the broth it produces.

Route generation treats the bioreactor as a fixed first step and searches downstream of whatever it makes, so the broth is the real input to the search

• every candidate route, every yield and every cost is conditioned on it. It used to be computed invisibly inside the search, which meant an oxygen-limited design producing a third of the requested titer generated a purification train for a broth the user had never seen and would not have accepted.

This endpoint exists so that broth can be put in front of the user and agreed before the search spends a minute on it.