Co gwarantuje keyof T w typie Column<T>?

type Column<T> = {
  key: keyof T;
  header: string;
  render?: (value: T[keyof T], row: T) => React.ReactNode;
};

interface TableProps<T> {
  data: T[];
  columns: Column<T>[];
}

function Table<T extends Record<string, unknown>>({ data, columns }: TableProps<T>) {
  return (
    <table>
      <thead>
        <tr>{columns.map(col => <th key={String(col.key)}>{col.header}</th>)}</tr>
      </thead>
      <tbody>
        {data.map((row, i) => (
          <tr key={i}>
            {columns.map(col => (
              <td key={String(col.key)}>
                {col.render ? col.render(row[col.key], row) : String(row[col.key])}
              </td>
            ))}
          </tr>
        ))}
      </tbody>
    </table>
  );
}