Screenshot pixels per logical pixel for every run of this package —
3 renders retina captures, at roughly the device ratio's cost in
time and bytes. Null means 1, the measured sweet spot; a run's own
capture-scale argument still wins.
Where this package keeps its scenarios, relative to the package. When
null, discovery walks all of test/ — a scenario is an ordinary widget
test and may sit next to the rest of them — and new writes to
test/scenarios. Declaring a directory narrows both to it.
The locale tags this app supports — ['en', 'fr'] — offered by the
language axis. Null means the axis offers no list and runs stay on the
platform default.
The folder's clock. ScenarioTime.real() runs it on the wall clock with
real sockets, one guest per scenario. Must agree with the folder's own
runScenarios(time: …); the harness refuses at probe when they differ.
Null is ScenarioTime.fake.
