LAYOFF ended after a single pick, so turning off five layers took five command
invocations. AutoCAD's Layer Off keeps prompting: you pick object after object
and the command ends on Enter or Esc only.
`SelectRun` grows a `repeat` mode next to the existing single-pick and plain
select modes: `SelectRun::repeat(..)` acts on every pick, seeds the next prompt
straight away, and finishes on Enter (or Esc through the usual cancel path).
The non-repeating paths are untouched — a repeating run must not let one pick
end the command, so `sel.single` is disabled for it and Enter is handled before
the selection machine's own keywords.
The whole run stays a single undo step, because the command body is still
called once per pick but the running command records one step, as before.
Tests: `crates/engine/tests/layoff_repeat.rs`
cargo test -p cadcraft-engine --test layoff_repeat -> 4 passed
- keeps asking until Enter, two layers off, one undo takes both back
- Esc ends it and keeps what was already turned off
- an empty pick ("0 found") keeps it running
- pickfirst and JSON calls are unchanged
Co-authored-by: kostyk348 <kostyk348@users.noreply.github.com>
