Add new leads to careCycle. To track which source each lead came from, create the source in careCycle first, then pass sourceId and optional leadCost with each record.

Response: For each successfully uploaded record, results contains the full customer record (same shape as the customer.created/customer.updated webhook). Lead upload does not handle policies, so no policies are returned; use /v2/sync/aca or /v2/sync/medicare for policies.