Ten tests, five of which fail on the build before this. The desktop
guard is meant to pass there -- that is its job, and it is the one that
caught a three-pixel regression nothing else could see.
`openTheQueue` moves to the fixtures, because hiding one button failed
ten tests in four files about the back stack and about layout: every
one of them opened the queue by clicking `#queue-button`, and so was
quietly asserting *which* route exists as well as what the queue does.
The route differs by width now and that is the feature.
Two smaller things. The play button is named for its action, so an
exact 'Play' waits out a fixture track -- 11.1s per test, passing by
luck, and it would have failed outright against LONG_TRACK. And the
"nothing playing" case clears the queue itself rather than trusting the
app not to have played anything: `make e2e` runs one long-lived app
across every spec (#168), which is how a deterministic bug first showed
up as a flake.