ActiveRecord::RecordInvalid: Validation failed: Advice markdown can't be blank (ActiveRecord::RecordInvalid)

## Error

```
Validation failed: Advice markdown can't be blank (ActiveRecord::RecordInvalid)
```

## Stack trace

```
active_record/validations.rb:84 in raise_validation_error
active_record/validations.rb:55 in save!
active_record/transactions.rb:313 in block in ActiveRecord::Transactions#save!
active_record/transactions.rb:365 in block in ActiveRecord::Transactions#with_transaction_returning_status
active_record/connection_adapters/abstract/database_statements.rb:342 in transaction
active_record/transactions.rb:361 in with_transaction_returning_status
active_record/transactions.rb:313 in save!
active_record/suppressor.rb:56 in save!
active_record/associations/collection_association.rb:371 in insert_record
active_record/associations/has_many_association.rb:63 in insert_record
```

## Tracking Details
- **Project**: exercism-rails
- **Sentry**: [ActiveRecord::RecordInvalid: Validation failed: Advice markdown can't be blank (ActiveRecord::RecordInvalid)](https://thalamus-ai.sentry.io/issues/117123691/)
- **Culprit**: SPI::ChatGPTResponsesController#create
- **First seen:** May 3, 2026