Adds multiple rows to an audience in a single bulk operation. Use this endpoint when importing contact or company records into an existing audience — for example, after a CRM export, a CSV upload, or a manual list build. Each row in the request body specifies cell values keyed by columnId. You cannot provide values for id columns — these are system-generated. By default, runEnrichment is false — enrichment does not run automatically after rows are created; set it to true in the request metadata to enable it. To enrich only specific columns on creation, provide columnId values in the metadata columns field; if omitted, all enrichable columns are processed. This operation is asynchronous. Returns 202 Accepted with a jobId. Poll the Get Bulk Job Status endpoint at GET /v1/audiences/{audienceId}/rows/actions/bulk/job/{jobId} using that jobId to confirm when all rows have been created and enrichment is complete. Returns 400 if the request body is malformed or columnId references are invalid.