Keep the cell args a declared column list states

[johanrd]

On top of universal-ember#202 (cfbb714). Independent of #4 and #5.

ColumnMetaOf has a branch for a column list that is a plain array — "A list with a declared type keeps that type". CellArgsOf has no such branch: it always derives the args from the Cells of the list. A plain array has no Cells to read, so the args are lost.

This stops a shared table component, which takes a column list from its caller and builds the table itself:

function makeTable<T, CellArgs>(
  columnConfigList: ColumnConfig<T, unknown, unknown, CellArgs>[],
  data: T[],
) {
  // error: the list is not assignable, because its args cannot be read back
  return headlessTable({}, { columns: () => columnConfigList, data: () => data });
}

The args now come from the config through a type-only property, the way the row type already does. A list written in place still reads its Cells, so nothing that infers today changes.

generic-wrapper.test.ts covers it. The package, its type tests and test-app are clean.

Cowritten by Claude

[johanrd]

superseded by universal-ember#203