Added labels to crate sidebar metadata

[psg-19]

This PR addresses #12668 by adding descriptive labels ("Last Updated" and "Size") to the metadata fields in the crate sidebar. This improves clarity for users by explicitly identifying what the date and byte values represent.

• app/components/crate-sidebar.gjs -> Added label elements for "Last Updated" and "Size" within the metadata section.
• app/components/crate-sidebar.css -> Added a ._label class to style the new labels with consistent font weight and spacing.
• tests/acceptance/crate-test.js -> Updated acceptance tests to verify that the new labels are correctly rendered on the crate page.

[Turbo87]

why did you use visible labels instead of tooltips like some of the other metadata fields are using?

[psg-19]

Thanks for the review.
The issue suggested "hover does not work well on mobile", so I thought to use visible labels.
I will make the changes using tooltips.

[Turbo87]

The issue suggested "hover does not work well on mobile"

yeah, but our tooltips are built in a way where clicking on the thing also displays the tooltips, so I'm not sure that comment actually applied. admittedly tooltips are still not a perfect pattern, but changing that is a bigger discussion, so in this case consistency seems more important for now.