Add Quick Start WebXR e2e baseline

[arussell-nvidia]

Summary

• Add a Playwright baseline for the Quick Start desktop browser path through the WebXR client.
• Serve IWER and @iwer/devui from local npm packages during the test so CI does not depend on unpkg availability.
• Gate the existing CloudXR web-client build action with the new e2e test after Jest.

Validation

• npm test
• USE_LOCAL_WEBXR_ASSETS=0 npm run build
• npm run test:e2e
• SKIP=check-copyright-year pre-commit run --all-files

Summary by CodeRabbit

• New Features

  • Added end-to-end browser coverage for the WebXR client's quick start flow.
  • Automated checks now verify the connection screen, browser XR support, and launch readiness in a desktop Chromium environment.

• Bug Fixes

  • Improved test setup to ensure required browser dependencies are installed before running the web client's end-to-end checks.

• Chores

  • Added project configuration and scripts to support running Playwright tests locally and in CI.

[coderabbitai]

📝 Walkthrough

Walkthrough

The web client gains Playwright end-to-end test support. The change adds a Playwright config, a new npm script and dev dependencies, a quick-start e2e test, and CI steps to install Chromium browser dependencies and run the new test target.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately reflects the main change: adding a Quick Start WebXR end-to-end baseline test.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/cxr-3577-quickstart-e2e

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