Mirror the `job` flag on the manual lifecycle: `vm new --start` was
hardcoded headless; add --gui/--nogui (default --nogui) so a clone can be
booted into the Workstation GUI window for interactive debugging. The
start banner reflects the mode.
Also update the runbook: §4.1 shows the --gui variant, and §3 notes that
the burnin-dummy build.sh is a ~30s fake build writing dist/build-info.txt
so the examples exercise the full pipeline.