Expose a column's alignment to the editor

A `createState` handle is an identity rather than a description: state
written under one is invisible to another built from the same arguments.
So the control that edits a column's alignment cannot declare its own,
and `alignState` has to leave the dialect by the front door.

The row limit gets the test its counterpart already had. Both matter
more than they read: a table past either is refused by the server, which
cannot undo the update and so rotates the room's epoch.