Enter appended its newline to the end of the value regardless of where
the caret was, so pressing it in the middle of `abc|def` produced
`abcdef` with a trailing blank line rather than splitting the text, and
a selected range was kept rather than replaced. That is a rewritten
value, not just a misplaced caret, and no editor behaves that way.
Split at the field's own selection and replace any selected range, then
mount the text area with the caret just after the inserted newline —
EnlargedStringField takes an explicit caretAt for this. Pointer
activation passes none and keeps falling back to end-of-value, since a
click carries no meaningful position. The maxLength check now prices the
resulting value, so replacing a selection can free the room the newline
needs.
The two maxLength tests were asserting against a stub onChange, which
froze the value and made "it did not change" pass whatever the component
did. They now run on a seeded stateful harness, with a no-maxLength
control so the constraint is shown doing the work.
Signed-off-by: cliffhall <cliff@futurescale.com>