Start Bulk Sync Execution

Starts a new execution of a bulk sync. This endpoint returns the execution record immediately after the run is queued or started. Use the execution ID with the bulk-sync execution endpoints if you need to monitor progress in detail. ## Execution modes - Set `test=true` to validate the sync without writing to the destination. - Use `resync_mode` for destructive or full-refresh style reruns. - `test` and `resync_mode` are mutually exclusive. The legacy `resync` boolean is no longer accepted on this v5 endpoint. Send `resync_mode` instead. If another execution is already running, the endpoint returns `409 Conflict`.