Add top-level `vmgui` to open the VMware Workstation GUI (renamed from the
earlier `vm open`). --vmx is optional: with it the GUI opens that VM, without
it the GUI starts bare. Power-on/fullscreen flags ignored (with a notice) when
no VMX is given. Needs an X display — sudo -u ci-runner strips $DISPLAY, so
--display / xhost; see runbook §4.7. 9 tests; suite green ≥90%.
Rewrite docs/RUNBOOK-PhaseC.md as a full manual-command reference: every
ci_orchestrator command with a working example as the ci-runner user, the `ci`
alias setup, quick-reference table, manual VM lifecycle (incl. vm open GUI
launch with the xhost/--display procedure), templating, maintenance, Phase C
testing, cutover checklist and a troubleshooting map.
Simone