fix: update FilteredActionList skeleton to use deterministic widths

[joshblack]

Changelog

New

N/A

Changed

• FilteredActionList body skeleton rows now use deterministic CSS-module widths instead of render-time randomness, making the loading state SSR-compatible.
• Kept VRT snapshot updates scoped to FilteredActionList loading states only.

Removed

• Removed the redundant FilteredActionListBodyLoader test asserting that Math.random is not called.
• Reverted unrelated VRT snapshot updates for ActionMenu and Avatar.

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

• npx vitest run packages/react/src/FilteredActionList/FilteredActionList.test.tsx
• npm run format:diff
• npm run lint
• npm run lint:css
• npm run type-check
• npm run build
• npm test -- --run
• Storybook started successfully and responded for /?path=/story/components-filteredactionlist--default

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github-ui (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: 467870c

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

This PR includes changesets to release 1 package

Name	Type
@primer/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

[github-actions]

⚠️ Action required

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Check the integration testing docs for step-by-step instructions. Or, apply the integration-tests: skipped manually label to skip these checks.

To publish a canary release for integration testing, apply the Canary Release label to this PR.

[primer]

🤖 Lint and formatting issues have been automatically fixed and committed to this PR.

[Copilot]

Pull request overview

This PR makes FilteredActionList’s body-loading skeleton SSR-compatible by removing render-time randomness and replacing it with deterministic, CSS-driven widths.

Changes:

• Replace Math.random()-based skeleton text widths with deterministic widths defined via CSS custom properties and :nth-of-type() rules.
• Apply a row class to drive deterministic width variation across skeleton rows.
• Re-enable VRT coverage for the “loading” Storybook stories and add a patch changeset entry.

Show a summary per file

File	Description
packages/react/src/FilteredActionList/FilteredActionListLoaders.tsx	Removes random width generation and applies a row class to enable deterministic skeleton styling.
packages/react/src/FilteredActionList/FilteredActionListLoaders.module.css	Adds deterministic width rules for skeleton rows via a CSS variable + :nth-of-type() pattern.
e2e/components/FilteredActionList.test.ts	Re-enables VRT snapshots for loading-related stories now that rendering is deterministic.
.changeset/filtered-action-list-skeleton-widths.md	Adds a patch changeset describing the consumer-facing SSR stability improvement.

Copilot's findings

• Files reviewed: 4/37 changed files
• Comments generated: 1

[joshblack]

@copilot remove the snapshot changes that are not related to FIlteredActionList (they should not change from what we already have)

[Copilot]

@copilot remove the snapshot changes that are not related to FIlteredActionList (they should not change from what we already have)

Done in e39811e — I reverted the unrelated ActionMenu and Avatar snapshot updates so this PR only keeps FilteredActionList-related snapshot changes.