Task 419: Fix Data Consistency Issues Found by Validation Tests

Status: DONE

Summary

Task 418 validation tests discovered data consistency issues:

1. EP02 speakers.json missing guest-esper speaker (present in dialogue file)
2. EP05 onscreen_data.json uses different schema (missing schemaVersion, different summary structure)

Fix these to align all data files with consistent schemas.

Rationale

• Consistent schemas simplify parsing and reduce special-case handling
• Missing speaker definitions could cause rendering issues
• Data discovered by automated tests should be fixed systematically