Implement replay diagnostics capture, failure categorisation, and artefact linking

[kalen-releasedgroup]

Summary

Capture the evidence required to make replay failures actionable rather than opaque.

Scope

• Capture replay diagnostics including timestamps, environment/browser settings, screenshots at failures, locator attempts, and assertion results.
• Classify failures into the required categories.
• Link diagnostics artefacts back to replay runs and scenario versions.

Requirement Links

• FR-REP-002, FR-REP-003
• Sections 7.4, 13.3

Dependencies

• Replay execution
• Artefact storage

Exit Criteria

• Failures have categorized summaries.
• Replay runs retain diagnostic evidence and artefact links.
• Diagnostics support author investigation from the UI.