RUNBOOK §15: dual-boot operation — Linux⇄Windows switch procedure, per-OS
CI-stack table (roots/runner/vmrun), current GRUB behaviour (DEFAULT=0,
TIMEOUT=0 hidden → boots straight to Linux), post-boot verification commands
for both OSes, and an optional GRUB tweak (left unapplied — boot-to-Linux is
intentional so the box returns as the Linux CI host after any unattended
reboot).
Checklist: Passo 9 done; fixed the stale global tracking table (Passi 6–9
were still [ ] despite being complete). Phase B is now fully closed (1–9 [x]).