On small screens, the PosePicker opens down, and we put the tabs on the
top, to be near the button.
On large screens, the PosePicker opens up, and we put the tabs on the
bottom, to be near the button.
Previously, we always set `placement="bottom-end"`, which on small
screens behaved as written, and on large screens there would not be
space to open downward so it would open upward instead.
Now, we set the placement explicitly based on a media breakpoint, and
we change the `flexDirection` of the tabs container on the same media
breakpoint.
Emi Matchu
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