Simplify data exchange to deliver inline data on confirm

[Tomeshwari-02]

Summary

• Move the primary data-exchange example flow from status polling to inline delivery on on_confirm
• Update both data-exchange use cases, their workflows, and the checked-in Postman collections to match
• Remove the old status-only example files so the generated artifacts stay aligned with the simplified flow

Validation

• Parsed the updated YAML workflow files successfully
• Parsed the updated JSON example and Postman collection files successfully

Notes

• This keeps the devkit focused on the shorter discover-to-confirm path with inline dataPayload delivery