v0.48.0

Report honesty + data preconditions. (1) Under --concurrency the per-scenario 'other' time bucket is really idle contention (waiting for a slot), so it's now labeled 'contention' and each scenario shows an 'active' ms figure — its own work, stable across concurrency. (2) Scenario 'requires: [...]' documents data preconditions (the seed data a scenario assumes), rendered in the report so a break from missing data is legible.