Feature Request 🛍️

Add an "Auto-generate sample data" button to the JSON Data panel that parses the current Concerto model and instantly populates the data editor with well-typed sample JSON.

Context

• This feature auto-generates valid sample data.
• New users often struggle with data shape, nested concepts, and the $class requirement.
• The playground supports hands-on experimentation with Accord Project templates.
• Manually creating schema-compliant JSON is the primary usability barrier.
• It improves accessibility for beginners and speeds up workflows for experienced users.

Use Case

When a user creates or modifies a Concerto model in the playground, they should be able to click a single button in the JSON Data header to auto-generate valid sample data matching the model schema. The generated strings use a sample_fieldName (e.g., sample_city, sample_name) so users can easily replace all placeholders in one go. This removes the need to manually construct conforming JSON.