How do I use variables in the API Management (Query Params, Headers, Body)?

In Settings → API Management, in Query Params, Headers, and Body fields, use the variable picker to insert {{local:Name}}, {{global:Name}}, etc. Variables are loaded from Variable Management (or from workflowData.variableConfig when the modal has not been opened yet). The picker is constrained to the viewport and shows categories (Local, Global, Constant, System, Data Profile). Test the API with Test API after setting variables.