Two faults in the Enter path, both found in review.
The split read `values[fieldName] as string`, a cast over a
Record<string, unknown> fed by whatever a server's schema declares. A
string field holding a non-string default renders as text and then threw
on `.slice`, so one keystroke crashed the panel. Read the control's own
value instead: always a string, and the exact string the selection
offsets index into.
The caret was recorded only when the newline fit, so pressing Enter mid
value in a field at its maxLength enlarged without one and threw the
caret to the end — a second surprise on top of the newline that did not
arrive. Record it on both paths, `start + 1` after an insertion and
`start` otherwise.
Signed-off-by: cliffhall <cliff@futurescale.com>
1d3b973742