FLX-2303: journey step budget exhausted

Family: plan/replay binding (the 2000 band)

One subject's journey took more steps than the run's declared budget. The budget exists so a state machine whose transitions cycle cannot make a run's length depend on its data; exhausting it means the Journey and the JourneyTaxonomy describe a cycle the engine will not silently truncate.

Look it up offline

$ fluxsim explain FLX-2303

Every code is listed in the error index.