- Allow POST /flows/0/assistants/ to create a new flow together with the assistant, mirroring the existing GraphQL createAssistant(flowID: 0) behavior
- Require both assistants.create and flows.create permissions when flowID=0
- Add explicit flow ownership check for non-zero flowID using flows.admin scope
- Load flow data in the response by fetching it via assistant.FlowID after creation, ensuring AssistantFlow is fully populated in all cases