Add many rows to a list in one call

Appends rows, each with its cells, in one transaction: the whole batch lands or none of it does. rows is an array, each entry a map of columnId to value (string, number, boolean or null); a row may omit any column. The per-call limits are the MCP tool bulk_create_workspace_rows' own, a row ceiling and a cell ceiling, whichever is reached first; a batch over either is refused with 400 BULK_ROWS_SIZE, whose message names the ceiling and how many rows of this width fit. An unknown column id is 400 COLUMN_NOT_IN_TABLE and the row quota is checked for the whole batch (402 LIST_ROW_LIMIT_REACHED), and a batch that would take the list past the platform row ceiling per list is 422 SYSTEM_LIMIT_REACHED; none of these writes anything. Gated like adding one row (CONTRIBUTE on the list); JWT only (the workspace router denies PATs). Workflows do NOT run for these rows.