Fix Explore category tab label cropping

[cjc0013]

Summary:

• Add stable vertical padding and centered alignment to the Explore category tab scroller.
• Give tab labels a minimum height and line height so category text is not cropped.

Test plan:

• git diff --check
• Attempted npm ci --ignore-scripts --no-audit, but npm is unavailable in this Codex shell.

Closes #2

[AbbeyIT]

Will check on this @cjc0013. Can you comment in the issue section? So I can put you in the assignee there.