🐛 [BUG] - Border radius on minimal card variants are too large

[rezrah]

Describe the bug

Update the border radius on Minimal card variants from xlarge to medium.

xlarge is appropriate for normal card variants where a border is present but not minimal.

Site Design confirmed that medium is the correct size value.

Actual	Expected

Reproduction steps

1. Go to this page: https://github.com/resources/articles/ai
2. Click on or focus on a Card item
3. Observe that the focus outline is too close to the hovered thumbnail

Expected behavior

1. Card with `minimal` variants use `--brand-borderRadius-medium` CSS variable instead of `--brand-borderRadius-xlarge`

Screenshots

Browsers

No response

OS

No response