Typing UNITS ran the JSON form with no parameters, which changed nothing
and printed nothing. Typed or menu-invoked UNITS (no parameters) now opens
a Drawing Units dialog like QSELECT does: length type and precision, angle
type and precision, insertion units and a sample output. OK applies the
values through the `units` command; JSON calls run the command as before.
SETVAR had no prompts either, so `SETVAR LUNITS 2` ran with no name and
the remaining inputs were dropped. Space acting as Enter was not the
cause. SETVAR now asks "Enter variable name or [?]" and then "Enter new
value for NAME <current>"; `?` lists the variables, unknown names end the
command, and a value of the wrong type re-prompts.
sysvars::set now refuses variables that `get` derives from state
(DWGNAME, DBMOD, EXTMIN, ...) and keeps integer header variables integer,
so a typo can no longer store text in LUNITS.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>