good-first: restore visible keyboard focus on filter segment radios

[unjica]

Summary

Filter segment controls hide the keyboard focus ring, making keyboard navigation hard to follow.

File(s)

• apps/dashboard/app/components/dashboard/list-filters-ui.tsx (FilterSegmentItem)

Tasks

• Remove or replace peer-focus-visible:outline-none with a visible focus style on the styled segment
• Test on Errors, Events, Sessions, and Overview filter toolbars

Acceptance criteria

• Keyboard users can see which segment is focused
• No API/schema changes
• pnpm lint && pnpm test && pnpm build pass

Base branch

Open PRs against develop. See CONTRIBUTING.md.