Add missing CSS for KeybindingHint

[langermank]

Closes https://github.com/github/primer/issues/5970

Some CSS got lost in this sx removal PR. We didn't have any VRT tests to catch it so I added some.

[changeset-bot]

🦋 Changeset detected

Latest commit: cf09077

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@primer/react	Patch
@primer/styled-react	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Copilot]

Pull Request Overview

This PR restores missing CSS properties for the KeybindingHint component that were accidentally removed in a previous sx removal refactoring. The missing styles affected the visual appearance of keybinding hint components, including border radius, font size, padding, and line height.

• Adds back 4 missing CSS properties to the Chord component styling
• Introduces comprehensive Visual Regression Testing (VRT) and Accessibility Verification Testing (AVT) coverage to prevent similar regressions

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/react/src/KeybindingHint/components/Chord.module.css	Restores missing CSS properties for border-radius, font-size, padding, and line-height
e2e/components/KeybindingHint.test.ts	Adds comprehensive VRT and AVT test coverage across all KeybindingHint story variants and themes

[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[primer-integration]

👋 Hi from github/github-ui! Your integration PR is ready: https://github.com/github/github-ui/pull/4232

[primer-integration]

🟢 ci completed with status success.