[Ji-One1]

Saved results, event traces, and screenshots are hard to inspect as separate files. This optional PR turns existing run artifacts into an offline HTML report; the buyer CLI does not need it.

What this changes

• Add pnpm storefront-e2e:report, a bounded artifact loader, view model, renderer, styles, and client interactions.
• Show the latest run for each storefront URL and scenario separately from history. Count only latest runs in totals.
• Show saved verdicts, checkpoint details, actions, friction, Standard Events, final messages, and screenshot timelines. Reuse Hydrogen's SelectedOption type in the report model.
• Read the current flat country/language context as configured, not browser-verified, with fallbacks for older artifact shapes.
• Warn about invalid or missing artifacts and when the search-depth limit can hide runs. Refuse symlinked artifact files and directories, ignore paths stored in results, escape HTML text, and check links.
• Write an HTML file without starting a browser, server, or model or changing source run artifacts.

Developer impact

Optional internal tooling only; no published Hydrogen changes or changeset. Saved verdicts are displayed, not recalculated.

Risk

Reports keep saved strings unchanged and are private owner data, not sanitized material for sharing. Linked screenshots and JSON files must remain available at their relative paths. Hidden model reasoning and analytics are not added.

How to Test

1. Use Node 24 at the repository root with dependencies installed and saved CLI runs from the preceding PR.
2. Run pnpm storefront-e2e:report --input /absolute/path/to/artifact-root.
3. Open the printed file:// URL. Select runs, inspect history, filter the timeline, and open screenshots and artifact links. Compare the shown verdict and reason with result.json.

Stack: 15/15, optional. Previous: #4322. Not required by the runner.