Adds the REST surface for the #145 troubleshooting leftovers (#158 items 4-5):
- GET /api/playouts/{id}/blocks - blocks a block playout schedules
- GET /api/playouts/{id}/blocks/{blockId}/history - paged block history
- GET /api/playouts/history/{id} - decode a history row by id
- POST /api/troubleshoot/validate-schedule - validate sequential YAML
New MediatR queries GetPlayoutHistoryDetails (Either, 404 unknown row /
422 malformed JSON) and ValidateSequentialSchedule (wraps
ISequentialScheduleValidator, never throws). DecodePlayoutHistoryHandler
and the new by-id handler now share PlayoutHistoryDecoder. Regenerated
openapi/v1.json.
Refs #145#158
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
