Fix VideoPlayer accessibility issues

[joshfarrant]

Summary

Fixes two Sev-2 VideoPlayer a11y issues.

The styling of the controls bar is heavier than it was before, but it's necessary to achieve the required contrast.

List of notable changes:

• Improved contrast of VideoPlayer focus styles by making the focus outline thicker and offsetting it.
• Improved contrast of controls and title.
• To offset the heavier title bar styles, the title bar now hides while the video is playing. This should probably have been default behaviour from day 1.
• Made the video tooltip more efficient by being more judicious about when the event listener is added.

Steps to test:

1. Focus the VideoPlayer with the keyboard
2. Observe the focus styles

Supporting resources (related issues, external links, etc):

• https://github.com/github/primer/issues/3773
• https://github.com/github/primer/issues/3774

Contributor checklist:

• All new and existing CI checks pass
• Tests prove that the feature works and covers both happy and unhappy paths
• Any drop in coverage, breaking changes or regressions have been documented above
• New visual snapshots have been generated / updated for any UI changes
• All developer debugging and non-functional logging has been removed
• Related issues have been referenced in the PR description

Reviewer checklist:

• Check that pull request and proposed changes adhere to our contribution guidelines and code of conduct
• Check that tests prove the feature works and covers both happy and unhappy paths
• Check that there aren't other open Pull Requests for the same update/change

Screenshots:

Before	After

[changeset-bot]

🦋 Changeset detected

Latest commit: d5fc0a4

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

This PR includes changesets to release 6 packages

Name	Type
@primer/react-brand	Patch
@primer/brand-primitives	Patch
@primer/brand-e2e	Patch
@primer/brand-fonts	Patch
@primer/brand-config	Patch
@primer/brand-storybook	Patch

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[github-actions]

🔍 Design token changes found

View CSS variable changes

- --brand-videoPlayer-title-bgColor: linear-gradient(#01040966, var(--base-color-scale-transparent));
+ --brand-videoPlayer-title-bgColor: linear-gradient(180deg, #000000e6, #00000073 66%, transparent);

- --brand-videoPlayer-controls-bgColor: linear-gradient(var(--base-color-scale-transparent), #01040966);
+ --brand-videoPlayer-controls-bgColor: #000000bf;

- --brand-videoPlayer-range-bgColor-progress: var(--base-color-scale-blue-5);
+ --brand-videoPlayer-range-bgColor-progress: var(--base-color-scale-blue-4);

- --brand-videoPlayer-title-bgColor: linear-gradient(#01040966, var(--base-color-scale-transparent));
+ --brand-videoPlayer-title-bgColor: linear-gradient(180deg, #000000e6, #00000073 66%, transparent);

- --brand-videoPlayer-controls-bgColor: linear-gradient(var(--base-color-scale-transparent), #01040966);
+ --brand-videoPlayer-controls-bgColor: #000000bf;

- --brand-videoPlayer-range-bgColor-progress: var(--base-color-scale-blue-5);
+ --brand-videoPlayer-range-bgColor-progress: var(--base-color-scale-blue-4);

[github-actions]

⚠️ Visual differences found

Our visual comparison tests found UI differences.

Please review the differences by using the test artifacts to ensure that the changes were intentional.

Artifacts can be downloaded and reviewed locally.

Download links are available at the bottom of the workflow summary screen.

Example:

If the changes are expected, please run npm run test:visual:update-snapshots to replace the previous fixtures.

Review visual differences

[rezrah]

This is quite the change! The overlay is quite stark and now covers up a large part of the video underneath. If we're going this far, can we just position the control bar underneath the video instead of on top? Right now, it's eating into a lot of the video so I think everyone's losing out, and the opacity is barely going to be noticed (couldn't see it on my external display). Worth looping in a designer for second opinion too.