FIX: Show scenario run failure details

[Richard Lundeen (richlundeen)]

Summary

• add persisted run-level error and error_type fields to the canonical scenario progress header and frontend contract
• map the fields from ScenarioResult in the progress read path
• show the failure type and reason on failed scenario pages, with the existing generic message as a fallback for legacy rows

Example

Before

This run ended before all planned executable units completed. Finished executions remain available below.

After

Run failed (ValueError): Scenario initialization failed. Finished executions remain available below.