Two small polish items on the insights category surface.
The desktop explainer popover body rendered at 11px while the mobile
sheet used the larger `text-sm`, an uncomfortable and asymmetric read.
Lift the popover body to `text-xs` (12px) so both surfaces sit on the
type scale.
The `MetricTargetSummary` docstring claimed both the range and the
in-target share are hidden when the route flags `insufficientData`. The
range stays visible — only the share is suppressed. Correct the comment
to match the code.