Use local avatar image for VRT instead of external URL

[siddharthkp]

Problem

Fetching from the external URL failed a few times (possibly due to downtime or service degradation), causing VRT tests because of a fallback avatar. These failures were confusing to debug since the root cause was not immediately obvious

Solution

We already change the image from user avatars to primer avatar. On top of that, using a local image makes the tests more reliable and independent of network requests

Added update snapshots and there are no diffs 🎉

[github-actions]

⚠️ Action required

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[Copilot]

Pull request overview

This PR improves VRT reliability by avoiding flaky external avatar image fetches during Storybook-driven Playwright screenshots.

Changes:

• Adds a local mock-avatar.png asset under packages/react/static/.
• Configures the React Storybook to serve packages/react/static via staticDirs.
• Updates the Playwright Storybook visit helper to fulfill https://github.com/*.png avatar requests using the local image instead of redirecting to an external URL.

Show a summary per file

File	Description
packages/react/static/mock-avatar.png	Adds a local PNG to use as a stable avatar image in tests.
packages/react/.storybook/main.ts	Serves ../static assets from Storybook to enable local static asset usage.
e2e/test-helpers/storybook.ts	Switches avatar request mocking from external redirect to local route.fulfill({path}).

Copilot's findings

• Files reviewed: 2/3 changed files
• Comments generated: 1

[Copilot]

The route mock only matches https://github.com/*.png, but several VRT-covered stories still request avatars from https://avatars.githubusercontent.com/... (e.g. packages/react/src/Avatar/Avatar.stories.tsx). Those requests will still hit the network and can still flake, which undermines the goal of making VRT independent of external avatar fetches. Consider adding an additional page.route for https://avatars.githubusercontent.com/** (and any other avatar hosts you use) to fulfill with the same local image, or broadening the existing matcher accordingly.