Workflow runs: closer estimates and clearer results

A run's cost estimate is now worked out for the model the run will actually use, so the figure before you press Run is closer to the charge. A run you cancel stays cancelled, a run missing a required input is refused before anything is charged, and a step cut off at its length limit says so. The run page, its export and a shared run show the run's result instead of your own input, and step messages come out in the language you use the app in.